Over the past few weeks, cases of flu have begun to creep up across the U.S., with spikes in the southeast and south central part of the country. Flu hospitalizations are also on the rise. According to the Centers for Disease Control and Prevention’s influenza tracking team, all signs point to an earlier than usual flu season.
At the same time, hospitals across the country are filling up with children who’ve contracted RSV — a virus that causes common cold-like symptoms that can sometimes lead to serious illness, particularly in infants and older adults.
With the third Covid winter approaching, and public health precautions like masking and social distancing all but abandoned, the next few months could see the American health care system pushed to capacity by multiple surges in respiratory disease.
That’s why experts are advising that the best thing people can do to protect themselves and prevent their local hospitals from overflowing is to get immunized against the circulating viruses. Pfizer’s experimental RSV vaccine is still in testing, but Covid-19 and flu shots are now available to almost everyone.
Experts agree that the best time to get vaccinated is now, before these viral ripples build into waves. But there are other, more subtle questions of timing that scientists are still investigating, including whether time of day or combining vaccines matters. Here’s what we know and don’t know:
Does getting the flu and Covid shots together make either less effective?
Probably not. The science is clear that the human immune system is sophisticated enough to handle seeing more than one antigen at a time and responding in a robust way. And there’s a lot of data to support this, including from trials of combination vaccines like the MMR (measles-mumps-rubella) and DTap (diphtheria, tetanus, pertussis) shots, which have been in use in the U.S. for decades.
“The immune system is extraordinary at recognizing many things at the same time,” said Shane Crotty, an immunologist at the La Jolla Institute for Immunology. “Right now in your intestine alone, your immune system is dealing with 500,000 potential targets. Adding one more thing to that is usually just like a rain drop falling into the ocean.”
Vaccines work primarily by activating two types of adaptive immune cells. The first are B cells, which churn out antibodies that recognize bits of a bacteria or virus — in the case of SARS-CoV-2, its spike protein. The second are T cells, which roam the body and kill any infected cells as well as coordinate the activity of other immune system players.
If a person’s body has seen a particular virus before, either in the form of a vaccine or a prior infection, then a booster shot or an annual flu jab serves to activate the pre-existing populations of B cells that already carry the instruction manuals for making antibodies specific to those pathogens. In other words, the vaccines usually aren’t competing for immune resources. The human body also keeps a reserve of B cells capable of creating novel antibodies against any new threats.
“Most of the time you can give two vaccines together and it all works fine,” said Crotty. However, some vaccine components meant to boost the immune response, called adjuvants, can interact or interfere with other shots when given in combination. The mRNA Covid vaccines contain an adjuvant in the form of lipid nanoparticles, the flu vaccine doesn’t. Definitive evidence on how co-administering the two shots impacts either’s efficacy is not yet available.
That’s why Crotty advises people to get the flu and Covid shots in different appendages — arms for adults and older children, legs for young children. “The immune system certainly has no problem recognizing vaccines if given that way because it’s two different processes happening simultaneously in localized ways,” he said.
Related:CDC: Signs point to an early start for flu season, with cases already ticking up in parts of the U.S.
While there’s not much data from human studies yet, lab experiments suggest even combined shots don’t decrease efficacy. One study published last year showed that mice and ferrets simultaneously vaccinated against SARS-CoV-2 and H1N1 influenza produced the same levels of antibodies as animals that received the shots in sequence. When they were later infected with those viruses, both vaccination strategies protected the animals from severe disease.
In fact, some researchers are already investigating whether the two vaccines might be combined into a single shot. This summer, scientists in China reported that their combination SARS-CoV-2/influenza mRNA vaccine protected mice from co-infection with H1N1 and the Alpha and Delta SARS-CoV-2 variants.
The only reason to space them out, say experts, is if you’re someone who tends to experience more intense reactions to immunizations, things like muscle or joint pain, chills, and headache. It’s possible that those reactions can be exacerbated by getting both jabs at once. A CDC study published in JAMA in July found that among 981,000 individuals, getting a simultaneous flu shot and Covid-19 booster was associated with an 8% to 11% increase in such systemic side effects, compared with a Covid-19 booster alone.
“It’s important to get both, and to get them now if you haven’t already,” said Kawsar Talaat, a Johns Hopkins infectious disease physician and vaccine researcher. “Whether it’s separate or together, the important thing is just to get them.”
Does the time of day I get my shots matter?
That the immune system follows a roughly 24-hour rhythm has been known since the early 1960s. But only in the last decade or two have the circadian clocks that control the activity of immune cells become a field of intense study, including by vaccine researchers.
Studies in mice have shown that in the morning, T cells turn on genes that make molecules involved in recognizing antigens and cranking out clone armies of T cells that can go patrol the body for more of the foreign invaders. At night, they produce molecules that silence that response.
“It seems there’s a whole program in the T cells that makes them very efficient at responding in the day and being less efficient at night,” said Nicolas Cermakian, a chronobiologist at McGill University and the Douglas Research Centre in Montreal. In a 2019 PNAS study, his team showed that vaccines delivered during the day produced more T cell activation than those delivered at night.
Data from human studies, at least from the 10 or so that have been conducted so far, painted a more complicated picture. In a Cell Research paper published last year, researchers in China found that among 63 health care workers, those that received a shot of the Sinovac vaccine in the morning produced twice as many antibodies against SARS-CoV-2 as workers who got the jab in the afternoon.
But another study from the U.K. of 2,784 health care workers inoculated with either Pfizer’s or AstraZeneca’s Covid vaccine found that higher antibody levels were observed in people who’d received the shots in the afternoon.
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Perhaps the strongest evidence for an AM jab comes from a 2016 study of influenza conducted in the U.K. — the first large-scale randomized trial of vaccine timing. It found that among 276 older adults, those who received their annual influenza vaccination in the morning had a more than three-fold higher antibody response to one of the influenza strains than those who got the shot in the afternoon.
However, it’s still too early and the data too sparse to extract any sort of rules or recommendations. While it’s clear that the immune system responds to vaccines differently at different times of day, whether or not those enhancements translate to better protection against a viral threat remains unknown. And different types of vaccines may have their own biologically optimized timing. Still, said Cermakian, it’s worth studying. Because adjusting the timing of vaccination may be a simple and inexpensive way to get the most out of currently available vaccines, particularly in older adults who tend to have dampened immune responses.
“Even a two-fold improvement for older populations could be very beneficial,” he said. “Imagine only needing to get a Covid-19 booster once a year instead of every five or six months. It would make a big difference in terms of cost and in terms of making it easier for people to stay protected for longer.”
With SARS-CoV-2 continuing to evolve, and the vaccines most commonly used in the U.S. only offering short-term protection against Covid-19, it’s a strategy vaccine makers and regulators contemplating the future of boosters may need to consider. But for now, said Cermakian, you should worry less about what time of day to make a vaccine appointment, and more about getting a good night’s sleep in the run-up to it.
“Sleeping well in the days before a vaccine is one thing people should do to get a better response,” he said. “We know that being well-rested is a big plus.”
Will we have to keep getting Covid boosters every six months and flu shots every year forever?
No one can predict the future, but public health officials are starting to look ahead to what a long-term vaccination strategy for our multi-respiratory-virus reality might look like. If researchers can pull off the long-elusive universal flu vaccine approach, that would certainly be a game-changer. But Crotty’s latest work suggests that there might be technologically simpler ways to push people’s immune systems to evolve all the antibodies they might ever need.
In a paper published last month in Nature, Crotty and his colleagues discovered that if they inoculated rhesus monkeys with a modest amount of HIV protein slowly, over 12 days, that six months later, some of the animals’ B cells were still actively working on building immunity to HIV. In particular, they saw sustained activity of B cells called germinal centers, which are kind of like the body’s antibody evolution engine. These cells were keeping those bits of protein and passing them around, learning from them, and evolving a diverse menagerie of antibody-producing memory B cells in the background.
“Mimicking a viral infection by dosing over a longer time frame helps the vaccine engage more of the immune system — it does a much better job at recruiting rare B cells with rare antigen-recognizing properties,” said Crotty.
This approach might be overkill for a lot of pathogens that the immune system has a pretty easy time recognizing. But for bugs that cloak their key regions, or mutate very quickly, like HIV, influenza, and to some extent, SARS-CoV-2, then a longer vaccine dose could help overcome that, by giving the body’s immune system more time to come up with more potential ways of seeing the virus.
“We wanted to test whether time of exposure mattered or not, and it turns out it can matter a lot,” said Crotty. “For me the take-home message was that we helped reveal a process that we think happens fairly regularly and just hadn’t been realized or observed.”
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Once you've had your 1st dose you need to wait several weeks before getting your 2nd dose of the COVID-19 vaccination. You need to wait: 8 weeks (56 days) if you're aged 18 or over. 12 weeks (84 days) if you or your child are aged 5 to 17.Why do I have to wait 28 days after Covid for vaccine? ›
This is because evidence suggests that a 12-week gap may reduce the already extremely low risk of heart inflammation after a vaccine. The 12-week gap does not apply to children at higher risk from the virus, including those with health conditions and those who live with vulnerable adults, who should wait for 28 days.What is the difference between over 65 and under 65 flu vaccine? ›
The higher dose of antigen in the vaccine is intended to give people 65 years and older a better immune response to vaccination, and therefore, better protection against flu.How long does vaccine immunity last for Covid? ›
Earlier research from the CDC suggested that protection from the Pfizer and Moderna COVID-19 vaccines could start to fade around 4 months after a booster dose. Protection against COVID-19 hospital stays seemed to drop from 91% soon after receiving a booster dose to 78% at the 4-month mark.Is Pfizer or Moderna better? ›
Both of the mRNA vaccines available in the US are highly effective against severe COVID-19, but recent studies suggest that Moderna's elicits a stronger immune response and might be better at preventing breakthrough infections.What are the side effects of the 2nd booster shot? ›
- Pain, swelling, and redness on the arm where the shot was given.
- Muscle or joint pain.
- Swollen lymph nodes.
Research has not yet shown how long you are protected from getting COVID-19 again after you recover from COVID-19. Vaccination helps protect you even if you've already had COVID-19.Can you get Covid twice? ›
Reinfection with the virus that causes COVID-19 means a person was infected, recovered, and then later became infected again. After recovering from COVID-19, most individuals will have some protection from repeat infections. However, reinfections do occur after COVID-19.Can I get my Covid booster early? ›
You can have your seasonal booster if it's been at least 3 months since you had your previous dose. If you have not had a 1st or 2nd dose of the COVID-19 vaccine yet, you should have them as soon as possible.What is the stronger flu shot for seniors? ›
As of 2022, federal health officials recommend specific flu vaccines for people age 65 and older. These vaccines are Fluzone High-Dose Quadrivalent, Flublock Quadrivalent, and Fluad Quadrivalent. Studies have shown it triggers a better immune response in older adults than the traditional flu vaccine.
- Soreness, redness, and/or swelling from the shot.
- Muscle aches.
The senior flu shot is considered safe, but it may cause mild side effects related to inflammation and the body's immune response. During the week after getting the vaccine, seniors may experience the following symptoms: Soreness, tenderness, redness, or swelling at the injection site. Headache or muscle aches.Who shouldn't get the Covid vaccine? ›
If you are allergic to PEG, you should not get an mRNA COVID-19 vaccine. Ask your doctor if you can get the J&J/Janssen vaccine. If you are allergic to polysorbate, you should not get the J&J/Janssen COVID-19 vaccine. Ask your doctor if you can get an mRNA COVID-19 vaccine.Does the Covid vaccine work against Omicron? ›
"Based on the data supporting their authorizations, the bivalent COVID-19 vaccines are expected to provide increased protection against the currently circulating omicron variant," says Dr. Sostman.Can you get Covid 3 times? ›
In fact, with the highly infectious omicron variant in circulation, it's becoming less unusual to have COVID-19 three times — or even four.Which booster is best for Omicron? ›
1 bivalent booster had a better immune response against COVID-19 Omicron subvariant BA. 1 compared with those who received the original (monovalent) booster.What is the most effective vaccine in history? ›
Smallpox vaccination with vaccinia virus is the most famous example of a highly effective vaccine and at the time when people were faced with smallpox outbreaks, this vaccine was associated with each of these characteristics that led to the implementation of a successful vaccine.How is Pfizer different from Moderna? ›
Despite their similarities, the Moderna doses have more than three times the amount of mRNA material (100 micrograms), compared to Pfizer (30 micrograms). The dose spacing is also different: three weeks apart for Pfizer and four weeks for Moderna.Why should you not take ibuprofen after Covid vaccine? ›
It is not known how over-the-counter (OTC) medicines, such as ibuprofen, aspirin, or acetaminophen, might affect how well the vaccine works. You may be able to take these types of medications to reduce fever or pain after you get your vaccine to relieve any pain or discomfort resulting from possible side effects.Is sore throat a side effect of Covid booster? ›
Some of the side effects of the vaccine are similar to symptoms of COVID-19. The vaccine will NOT cause or give you COVID-19. Symptoms such as a sore throat, runny nose, or cough are NOT side effects of the vaccine.
Apply a clean, cool, wet washcloth to your arm to help reduce pain. It may also help to exercise your arm. If you have a fever, drink plenty of fluids and dress lightly. Over-the-counter medicines like Tylenol® (acetaminophen) or Motrin® or Advil® (ibuprofen) can help with pain, fever, headache, or discomfort.Can a person be immune to Covid? ›
Getting COVID-19 offers some natural protection or immunity from reinfection with the virus that causes COVID-19 . It's estimated that getting COVID-19 and COVID-19 vaccination both result in a low risk of another infection with a similar variant for at least six months.Do dogs get Covid? ›
The virus that causes COVID-19 can spread from people to animals during close contact. Pets worldwide, including cats and dogs, have been infected with the virus that causes COVID-19, mostly after close contact with people with COVID-19. The risk of pets spreading COVID-19 to people is low.Should I get vaccinated if I have already had COVID-19? ›
Yes, you can and should get the vaccine if you previously were infected with the COVID-19 virus. The CDC recommends you get vaccinated even if you have already had COVID-19 because you can catch it more than once.How long are you contagious with Omicron? ›
We know that people tend to be most infectious early in the course of their infection. With Omicron, most transmission occurs during the one to two days before onset of symptoms, and in the two to three days afterwards.How long do Omicron symptoms last? ›
How long do omicron symptoms last? Most people who test positive with any variant of COVID-19 typically experience some symptoms for a couple weeks.How many times can I catch Covid? ›
Can you get Covid-19 twice? Yes, it is possible to get Covid-19 two, three or even more times. Covid reinfections have become more common because of the Omicron variant, and because immunity from previous infection and immunisation has reduced over time.Can I choose which vaccine I get? ›
You cannot usually choose which vaccine you have. If you book online, you'll only be offered appointments for vaccines that are suitable for you. Most people can have any of the COVID-19 vaccines, but some people are only offered certain vaccines.Is a booster the same as the first shot? ›
No. An additional dose is different from a booster dose. Some people, those who are immunocompromised, may not develop the same immune response level after vaccination as others, so they made need an additional dose before their booster. A booster dose is recommended as protection from the vaccine may wane over time.Can you get a vaccine if you are ill? ›
If you are unwell, it is better to wait until you have recovered to have your vaccine, but you should try to have it as soon as possible. You should not attend a vaccine appointment if you are self-isolating, waiting for a COVID-19 test or unsure if you are fit and well.
Some high-dose flu vaccines include 3 to 4 times as much flu virus antigen — the part of the vaccine that stimulates the immune system — as standard flu vaccines. One flu vaccine recommended for older adults has the same amount of antigen as the standard dose vaccine.How long after flu shot do you feel tired? ›
Common reactions to vaccines are normal and can include soreness, redness and swelling where the vaccine was given. Other symptoms can include fever, headache, aching muscles and fatigue that may last 1 to 2 days.How long after a flu jab can you get side effects? ›
Fever after the vaccine
This normally happens within 48 hours of the vaccination and usually goes away within 48 hours. If the fever starts more than 48 hours after the vaccination, or lasts longer than 48 hours, you should seek medical advice as you may have coronavirus or another infection.
The experts looked at research studies to determine whether influenza vaccines increase the risk of developing neurologic conditions such as multiple sclerosis, Guillain-Barre syndrome, and optic neuritis, and concluded that vaccines did not raise the risk.Does flu shot cause high blood pressure? ›
Can flu jab increase blood pressure? There is no evidence that the influenza vaccination increases blood pressure, however for people who have hypertension or underlying cardiac conditions, getting the flu can elevate the risk of significant health issues.How soon after a flu shot can you take Tylenol? ›
“Unless your health care provider tells you otherwise, it's best not to take pain relievers one or two days before the flu vaccine and for a week afterward,” said David J. Topham, Ph. D., a study author and professor in the Center for Vaccine Biology and Immunology at URMC.Can flu shots blur vision? ›
We report the ophthalmological and laboratory findings of 6 patients who, after influenza vaccination, were affected by oculorespiratory syndrome (ORS), complaining of red eyes, photophobia, blurred vision, palpebral edema, ocular pain and itching, and conjunctival secretions.Can flu shot cause rapid heartbeat? ›
Serious Influenza Vaccine Side Effects
Symptoms can include swelling, hives, breathing difficulties, rapid heart rate, weakness, and dizziness. Patients experiencing these symptoms should contact their doctor as soon as possible and if very sever, call 911 or go to the closest emergency room.
This winter, people aged 65 and over are being offered a flu vaccine called Fluad®. This is the best vaccine currently available for people in this age group because it contains an adjuvant that helps the immune system create a stronger response to the vaccine.Which body system is most directly concerned with vaccination? ›
The immune system is an extremely important defence mechanism that can identify an invading organism and destroy it. Immunisation prevents disease by enabling the body to more rapidly respond to attack and enhancing the immune response to a particular organism.
Every adult should get a Tdap vaccine once if they did not receive it as an adolescent to protect against pertussis (whooping cough), and then a Td (tetanus, diphtheria) or Tdap booster shot every 10 years. In addition, women should get the Tdap vaccine each time they are pregnant, preferably at 27 through 36 weeks.What diseases don't have a vaccine? ›
But there is still — despite 30 years of effort — no AIDS vaccine. There is no universal flu vaccine. There are no vaccines with long-lasting protection against malaria or tuberculosis. None for parasites like Chagas, elephantiasis, hookworm or liver flukes.Is Pfizer or Moderna better? ›
Both of the mRNA vaccines available in the US are highly effective against severe COVID-19, but recent studies suggest that Moderna's elicits a stronger immune response and might be better at preventing breakthrough infections.Should you wait for Omicron booster? ›
You should get the Omicron booster as soon as you have recuperated and are no longer contagious, says Dr. Cunningham. “We used to recommend that everyone wait three months after recovering from COVID-19 to get a booster.Does second booster protect against Omicron? ›
529 and BA. 2 (Omicron) variant were predominant. These findings suggest that among nursing home residents, second mRNA COVID-19 vaccine booster doses provided additional protection over first booster doses against severe COVID-19 outcomes during a time of emerging Omicron variants.How long do COVID antibodies last? ›
Coronavirus Antibodies Fall Dramatically in First 3 Months after Mild Cases of COVID-19. A UCLA study shows that in people with mild cases of COVID-19, antibodies against SARS-CoV-2 — the virus that causes the disease — drop sharply over the first three months after infection, decreasing by roughly half every 36 days.What does your throat feel like with COVID? ›
Well, it can feel exactly the same as a cold, according to Brian Curtis, MD, vice president of Clinical Specialty Services for OSF HealthCare. That makes it hard to tell the difference between a cold and a mild case of COVID. It's even harder to tell the difference knowing that sore throat is a COVID symptom.How long does COVID natural immunity last? ›
(2021). Naturally acquired SARS-CoV-2 immunity persists for up to 11 months following infection. The Journal of Infectious Diseases.How long after first vaccine do you get second? ›
The Centers for Disease Control and Prevention (CDC) have advised that the second should be given no more than 8 weeks after the first dose. However, the CDC has also indicated that you do not need to start the shots over again if you go beyond the 8 week window for the second shot. It will still be effective.What gap should be left between 2 vaccines in the same muscle? ›
Where two or more injections need to be administered at the same time, they should be given at separate sites, preferably in a different limb. If more than one injection is to be given in the same limb, they should be administered at least 2.5cm apart (American Academy of Pediatrics, 2003).
ATAGI recommends a primary dosing schedule of the Pfizer ≥12 years vaccine or the Moderna ≥12 years vaccine of 2 doses, 8 weeks apart. The manufacturer's dosing schedule for Pfizer ≥12 years is 2 doses, at least 21 days (3 weeks) apart; and for Moderna ≥12 years, 2 doses, 4 weeks apart.Is it safe to get multiple vaccines at the same time? ›
Vaccines work just as well and are just as safe if you get them alone or with other vaccines. If you get side effects, they are generally the same whether you get one vaccine or more than one. So it is not expected to cause worse reactions.What happens if I only get 1 Covid vaccine? ›
If you skip your second shot, the short answer is that you aren't getting the best protection from the two-dose series. All of the clinical trial data that measured effectiveness is based on people getting both doses. So, we don't know the level of protection you'll get from only one shot.Is a booster the same as the first shot? ›
No. An additional dose is different from a booster dose. Some people, those who are immunocompromised, may not develop the same immune response level after vaccination as others, so they made need an additional dose before their booster. A booster dose is recommended as protection from the vaccine may wane over time.Can you get Covid twice? ›
Reinfection with the virus that causes COVID-19 means a person was infected, recovered, and then later became infected again. After recovering from COVID-19, most individuals will have some protection from repeat infections. However, reinfections do occur after COVID-19.Which vaccine is given on the left thigh? ›
Diphtheria-tetanus-acellular pertussis (DTaP) vaccine given in the thigh to children aged 3 years and younger presents a significantly lower risk of a local reaction needing medical attention than does intramuscular (IM) injection in the arm, a new study shows.Why is the Covid vaccine injected into the muscle? ›
Like most other vaccines, the COVID-19 vaccine should be given intramuscularly. Muscles have good vascularity, and therefore allowing injected drug to reach systemic circulation quickly, bypassing the first-pass metabolism.What pain reliever can I take after Covid vaccine? ›
Over-the-counter medicines, such as aspirin, antihistamines, or acetaminophen, may help relieve fever, pain, or discomfort after getting vaccinated—but should not be used before getting vaccinated.Does Novavax affect the heart? ›
Myocarditis and pericarditis
Myocarditis (inflammation of the heart) and pericarditis (inflammation of the membrane around the heart) can occur after Novavax.
Where is the Pfizer-BioNTech COVID-19 vaccine made? As of January 2022, the Pfizer-BioNTech COVID-19 vaccine is manufactured between 11 sites across five countries, including the U.S., Germany, Belgium, Ireland, and Croatia, and engages more than 20 suppliers.
You could experience soreness at the injection site, fatigue, headache, body aches, and fever. These symptoms don't last long — about 1 to 3 days. A serious but very rare side effect is heart inflammation.Which vaccines should not be given together? ›
In persons with anatomic or functional asplenia and/or HIV infection, quadrivalent meningococcal conjugate vaccine (MCV4)-D (MenACWY-D, Menactra) and pneumococcal conjugate vaccine (PCV)13 (PCV13, Prevnar 13) should not be administered simultaneously (27).Which group is influenza vaccine Not recommended for? ›
Children and the flu vaccination
Flu vaccines do not work well in babies under 6 months of age so it is not recommended. This is why it is so important that pregnant women have the vaccination – they will pass on some immunity to their baby that will protect them during the early months of their life.
Vaccines do not overwhelm or weaken a child's immune system. Instead, they make it stronger by providing protection against diseases. Even combination vaccines, which protect against multiple diseases, are easy for your child's immune system to handle.