The most typical questions on vaccination unwanted effects, answered.

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Tara Parker-Pope

Every day almost three million folks within the United States are getting the Covid-19 vaccine. And each new jab prompts new questions on what to anticipate after vaccination.

Last week I requested readers to ship me their questions on vaccinations. Here are some solutions.

Short-lived unwanted effects like fatigue, headache, muscle aches and fever are extra frequent after the second dose of each the Pfizer-BioNTech and the Moderna vaccines, which every require two photographs. (The Johnson & Johnson vaccine requires solely a single shot.) Patients who expertise disagreeable unwanted effects after the second dose typically describe feeling as if they’ve a foul flu and use phrases like “it flattened me” or “I was useless for two days.” During vaccine research, sufferers have been suggested to schedule just a few days off work after the second dose simply in case they wanted to spend a day or two in mattress.

Data collected from v-safe, the app everybody is inspired to make use of to trace unwanted effects after vaccination, additionally present a rise in reported unwanted effects after the second dose. For occasion, about 29 p.c of individuals reported fatigue after the primary Pfizer-BioNTech shot, however that jumped to 50 p.c after the second dose. Muscle ache rose from 17 p.c after the primary shot to 42 p.c after the second. While solely about 7 p.c of individuals received chills and fever after the primary dose, that elevated to about 26 p.c after the second dose.

The New York Times interviewed a number of dozen of the newly vaccinated within the days afterward. They recounted a large spectrum of responses, from no response in any respect to signs like uncontrolled shivering and “brain fog.” While these experiences aren’t nice, they’re an indication that your personal immune system is mounting a potent response to the vaccine.

An evaluation from the primary 13.7 million Covid-19 vaccine doses given to Americans discovered that unwanted effects have been extra frequent in girls. And whereas extreme reactions to the Covid vaccine are uncommon, almost all of the instances of anaphylaxis, or life-threatening allergic reactions, occurred in girls.

The discovering that ladies usually tend to report and expertise disagreeable unwanted effects to the Covid vaccine is per different vaccines as nicely. Women and ladies can produce as much as twice as many antibodies after receiving flu photographs and vaccines for measles, mumps and rubella (M.M.R.) and hepatitis A and B. One examine discovered that over almost three a long time, girls accounted for 80 p.c of all grownup anaphylactic reactions to vaccines.

While it’s true that ladies could also be extra more likely to report unwanted effects than males, the upper charge of unwanted effects in girls additionally has a organic rationalization. Estrogen can stimulate an immune response, whereas testosterone can blunt it. In addition, many immune-related genes are on the X chromosome, of which girls have two copies and males have just one. These variations could assist clarify why much more girls than males are bothered with autoimmune illness, which happens when a sturdy immune response assaults the physique’s wholesome tissue. You can learn extra about girls and vaccine unwanted effects right here.

Side results get all the eye, however for those who have a look at the information from vaccine medical trials and the actual world, you’ll see that many individuals don’t expertise any unwanted effects past a sore arm. In the Pfizer vaccine trials, about one out of 4 sufferers reported no unwanted effects. In the Moderna trials, 57 p.c of sufferers (64 or youthful) reported unwanted effects after the primary dose — that jumped to 82 p.c after the second dose, which suggests nearly one in 5 sufferers reported no response after the second shot.

An absence of unwanted effects doesn’t imply the vaccine isn’t working, mentioned Dr. Paul Offit, a professor on the University of Pennsylvania and a member of the Food and Drug Administration’s vaccine advisory panel. Dr. Offit famous that in the course of the vaccine trials, a big variety of folks didn’t report unwanted effects, and but the trials confirmed that about 95 p.c of individuals have been protected. “That proves you don’t have to have side effects in order to be protected,” he mentioned.

Nobody actually is aware of why some folks have quite a lot of unwanted effects and others have none. We do know that youthful folks mount stronger immune responses to vaccines than older folks, whose immune programs get weaker with age. Women sometimes have stronger immune responses than males. But once more, these variations don’t imply that you simply aren’t protected for those who don’t really feel a lot after getting the shot.

Scientists nonetheless aren’t certain how efficient the vaccines are in folks whose immune programs could also be weakened from sure medical circumstances, resembling most cancers therapies or H.I.V. an infection or as a result of they’re taking immune suppressing medicine. But most specialists imagine the vaccines nonetheless supply these sufferers some safety in opposition to Covid-19.

The backside line is that regardless that particular person immune responses can fluctuate, the information collected up to now present that each one three vaccines authorised within the United States — Pfizer-BioNTech, Moderna and Johnson & Johnson — are efficient in opposition to extreme sickness and dying from Covid-19.

You shouldn’t attempt to stave off discomfort by taking a ache reliever earlier than getting the shot. The concern is that premedicating with a ache reliever like acetaminophen (Tylenol) or ibuprofen (Advil, Motrin), which might forestall unwanted effects like arm soreness in addition to fever or headache, may also blunt your physique’s immune response.

While it’s doable that taking a ache reliever earlier than your photographs may need dampened your physique’s immune response, vaccine specialists say you shouldn’t fear, and also you shouldn’t attempt to get one other shot. Studies of different vaccines counsel that whereas premedicating can uninteresting the physique’s immune response to a vaccine, your immune system can nonetheless mount a powerful sufficient protection to struggle an infection. A evaluate of research of greater than 5,000 kids in contrast antibody ranges in kids who took ache relievers earlier than and after vaccinations and those that didn’t. They discovered that ache relievers didn’t have a significant affect on immune response, and that kids in each teams generated ample ranges of antibodies after their photographs.

The excessive efficacy of all of the Covid vaccines means that even when taking Tylenol earlier than the shot did blunt your physique’s immune response, there’s some wiggle room, and you’re seemingly nonetheless nicely protected in opposition to Covid-19. “You should feel reassured that you’ll have enough of an immune response that you’ll will be protected, especially for vaccines that are this good,” mentioned Dr. Offit.

“It’s OK to treat” unwanted effects with a ache reliever, mentioned Dr. Offit, however for those who don’t really want one, “don’t take it.”

While most specialists agree it’s protected to take a ache reliever to alleviate discomfort after you get vaccinated, they advise in opposition to taking it after the shot as a preventive or in case your signs are manageable with out it. The concern with taking an pointless ache reliever is that it may blunt a few of the results of the vaccine. (In phrases of the vaccine, there’s no significant distinction for those who select acetaminophen or ibuprofen.)

During the Moderna trial, about 26 p.c of individuals took acetaminophen to alleviate unwanted effects, and the general efficacy of the vaccine nonetheless was 94 p.c.

Research and anecdotal studies counsel that folks with a beforehand identified Covid-19 an infection could have a stronger response and extra unwanted effects after their first dose of vaccine in comparison with those that have been by no means contaminated with the virus. A robust response to your first dose of vaccine additionally is likely to be an indication that you simply have been beforehand contaminated, even for those who weren’t conscious of it.

If you beforehand examined constructive for Covid-19 or had a constructive antibody blood check, be ready for a stronger response to your first dose, and contemplate scheduling just a few days off work simply in case. Not solely will it’s extra comfy to remain residence and get better in mattress, the vaccine unwanted effects can resemble the signs of Covid-19, and your co-workers received’t need to be close to you anyway.

Studies counsel that one dose is likely to be ample for individuals who have a beforehand confirmed case of Covid-19, however up to now the medical tips haven’t modified. If you’ve obtained the Pfizer-BioNTech or Moderna vaccines, it is best to plan to get your second dose even for those who’ve had Covid-19. Skipping your second dose may create issues in case your employer or an airline ask to see proof of vaccination sooner or later. If you reside in an space the place the single-dose Johnson & Johnson vaccine is out there, then you definately may be absolutely vaccinated after only one dose. You can learn extra right here in regards to the vaccine response in individuals who’ve had Covid-19.

The vaccines seem like efficient in opposition to a brand new variant that originated in Britain and is rapidly changing into dominant within the United States. But some variants of the coronavirus, notably one first recognized in South Africa and one in Brazil, seem like more proficient at dodging antibodies in vaccinated folks.

While that sounds worrisome, there’s motive to be hopeful. Vaccinated folks uncovered to a extra resistant variant nonetheless seem like protected in opposition to critical sickness. And scientists have a transparent sufficient understanding of the variants that they already are engaged on creating booster photographs that can goal the variants. The variants recognized in South Africa and Brazil are usually not but widespread within the United States.

People who’re vaccinated ought to nonetheless put on masks in public and adjust to public well being tips, however you shouldn’t stay in concern of variants, mentioned Dr. Peter J. Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston. “If you’re vaccinated, you should feel pretty confident about how protected you are,” mentioned Dr. Hotez. “It’s unlikely you’ll ever go to a hospital or an I.C.U. with Covid-19. In time you’re going to see a recommendation for a booster.”

I hope these solutions will reassure you about your personal vaccine expertise. You can discover a extra full record of questions and solutions in our particular vaccine device “Answers to All Your Questions About Getting Vaccinated Against Covid-19.”