US study reveals common side-effects after Pfizer and Moderna Covid booster shots

A new US study has revealed the side effects people experience after their Covid-19 booster shot, compared to how they felt after jab number two.

The side effects from booster shots of mRNA Covid-19 vaccines produced mild to moderate side effects similar to the second dose, according to an analysis from the US Centers for Disease Control and Prevention.

The US study was conducted when third-dose eligibility was limited to patients with moderate to severe immunocompromising conditions, about six months after their initial vaccine doses.

And it looked at booster shots for mRNA vaccines Pfizer and Moderna, which have been rolled out extensively in the US and approved for use in Australia.

The findings, released in the US on Tuesday, stemmed from data collected between August 12 to September 19 through v-safe, the CDC’s voluntary phone-based surveillance system, and included 22,191 registrants who reported receiving a third dose of the vaccine.

The side effects from mRNA Covid booster shots produced mild to moderate side effects similar to the second dose, according to a US study. Picture: Angela Weiss/AFP

It found most participants reported third dose side effects that were similar to those commonly experienced after the second jab, including arm pain, fatigue and headache, which generally set in the next day.

Nearly all registrants under study received a third dose that matched their first two doses, and for 12,591 registrants who completed a check-in survey, 79.4 per cent and 74.1 per cent reported local or systemic reactions, respectively, after the third dose, compared to 77.6 per cent and 76.5 per cent, respectively, after the second dose.

“These initial findings indicate no unexpected patterns of adverse reactions after an additional dose of Covid-19 vaccine; most of these adverse reactions were mild or moderate,” the report reads.

Across the board, the CDC’s v-safe data indicated a slight increase in local reactions after the third dose versus the second dose, and a slight decrease in systemic reactions after dose three versus dose two.

Most reports of pain after the additional dose were characterised as mild-to-moderate reactions (51.4 per cent and 41.9 per cent), and compared to 637 registrants (6.7 per cent) who reported severe pain, “defined as pain that makes daily activities difficult or impossible”.

Of the total 22,191 third dose recipients, about 28 per cent said they couldn’t “perform normal daily activities” most frequently the day after vaccination, while 1.8 per cent sought medical care and 0.1 per cent were hospitalised.

A new @CDCMMWR details a preliminary analysis of vaccine safety data that found no unexpected adverse reactions following an additional dose of mRNA #COVID19#vaccine, as well as mostly mild to moderate reactions from a third dose. Learn more: https://t.co/f2qTYFGeSw. pic.twitter.com/9QwPepdYzj

— CDC (@CDCgov) September 28, 2021

The survey didn’t capture reasons for medical attention or hospitalisation, however the report notes that CDC staff followed up with these registrants.

Dr Rochelle Walensky, director of the CDC, spoke to the findings during a White House briefing on Tuesday, adding the CDC and US Food and Drug Administration reviewed the report in informing the newly released recommendations for booster shots, which awarded expanded eligibility for the Pfizer vaccine booster across several high-risk groups about six months after the primary series.

The most common side effects were mild to moderate headache, fatigue and soreness in the injected arm. Picture: Robyn Beck/AFP

Health authorities are working to review similar data for recipients of other vaccines developed by Moderna and Johnson & Johnson, another Covid-19 vaccine used in the US.

“Covid-19 vaccine booster doses so far are well tolerated,” Dr Walensky said of the report, in part, adding: “The frequency and type of side effects were similar to those seen after the second vaccine doses and were mostly mild or moderate and short-lived.

“We will continue to evaluate data as it becomes available in real-time and with urgency and update our recommendations to make sure that all of those at risk have the protection they need.”

While third dose eligibility was limited to a small fraction of Americans with immunocompromising conditions during the study period, researchers suspected registrants included those with and without such conditions, and the v-safe surveillance system doesn’t include data about immune status.

This article originally appeared on Fox News and was reproduced with permission