As more people get vaccinated each day scientists are learning that not only is it safe to wait longer for the second dose of the Covid-19 vaccine but new research shows that people who’ve already been infected by the virus might only need a single shot of the vaccine.
The study, published in the New England Journal of Medicine, looked at 109 people with and without previous SARS-CoV-2 immunity. What they found was that those who had already contracted Covid-19 developed antibodies within days of the first dose of vaccine at a rate 10 to 20 times higher than those who were uninfected, and at a more than tenfold rate after the second dose.
“We showed that the antibody response to the first vaccine dose in people with pre-existing immunity is equal to or even exceeds the response in uninfected people after the second dose,” said co-author Viviana Simon in a statement. “For that reason, we believe that a single dose of vaccine is sufficient for people who have already been infected by SARS-CoV-2 to reach immunity.”
“These findings suggest that a single dose of vaccine elicits a very rapid immune response in individuals who have tested positive for COVID-19,” added Florian Krammer, co-author and professor of vaccinology . “In fact, that first dose immunologically resembles the booster (second) dose in people who have not been infected.”
The researchers also looked at systemic reactions after the first dose of vaccine in a second group of 231 people, 83 of whom had tested positive for Covid-19, and 148 who had not.
What they noticed was that while the vaccines were generally well tolerated by everyone, those who had previously had Covid-19 had more side effects, such as fatigue, headache, chills, fever, and muscle or joint pain, after the second dose of the vaccine.
Although there have been many reports of people experiencing worse side effects after the second coronavirus vaccine shot, this study suggests that the side effects are greater for those who already contracted the virus.
According to the researchers, the reason for the stronger response in both groups is likely due to the fact the body has already been “primed,” meaning the immune cells have learned how to recognize the spike protein of the virus — the antigen that forms the basis for vaccination. These cells thus respond more vigorously, leading to stronger reactions to the vaccine.
In response to this new finding, the researchers are calling for a change in public health policy to help spare these people unnecessary side effects as well as stretch the already limited vaccine supply.
Simon also suggested that if a persons infection history is unknown using a screening tool to test for the antibodies could help determine if the individual needs one or two doses.
“If the screening process determines the presence of antibodies due to previous infection, then a second shot of the coronavirus vaccine may not be necessary for the individual,” she concluded.
“And if that approach were to translate into public health policy, it could not only expand limited vaccine supplies, but control the more frequent and pronounced reactions to those vaccines experienced by Covid-19 survivors.”
This approach is already being considered in countries such as France and Canada after previous early research showed similar results.
However, some experts argue that there’s not enough data on the amount and length of protection these altered dosing schedules provide and that changing the dosage given without rigorous evidence could damage public trust in vaccines.
“We should really think long and hard any time we advise people to deviate from what the evidence actually shows in terms of efficacy, which has only been tested for those standard dosing regimens,” said Angela Rasmussen, a virologist at Georgetown University’s Center for Global Health Science and Security, in an interview with Scientific American. “Before we start tinkering with the vaccine regimens, we should worry about making sure that we can actually give people the vaccines that we already have.”
Currently, there are two approved Covid-19 vaccines (Pfizer-BioNTech and Moderna) which require two doses given three to four weeks apart.
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March 11, 2021 at 05:00AM
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People Who Already Had Covid-19 Might Not Need A Second Dose Of The Vaccine, Study Finds - Forbes
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