New C.D.C. data reveals evidence that boosters’ protection against severe Covid plunges after four months. According to CNBC, the study was an early look at the performance of Covid-19 booster shots during the recent omicron wave in the U.S. which showed a decline in effectiveness against severe cases, though the shots still offered “strong protection.”
The researchers looked at patient visits to hospitals and urgent care centers in 10 states. They estimated how well the booster prevented Covid-related visits to emergency departments and urgent care centers, and how well the vaccines prevented hospitalizations.
About 10% of people in the study were boosted. Vaccine effectiveness was higher in people who had received boosters than in people who had received only the original series of shots.
But researchers also found that during the time that the omicron variant has been predominant, vaccine effectiveness against outpatient visits was 87% in people who had gotten a booster two months earlier, but to 66% at four months after. Vaccine effectiveness against hospitalization fell from 91% at two months to 78% by the fourth month.
CNBC reported the U.S. booster campaign was based on evidence that emerged last year that vaccine protection was fading months after people got their initial vaccinations.
Still, that kind of finding was unforeseen, said Dr. William Schaffner, a Vanderbilt University vaccines expert.
“I’m a little surprised, according to the data, that it’s starting to wane already,” he said, adding that he would have anticipated higher estimates of vaccine effectiveness at the four-month post-booster mark.
The protection people experience after recovering from COVID-19, known widely as natural immunity, lasts for at least 18 months, according to a recently published study reported in The Epoch Times.
The Epoch Times reports researchers in Italy analyzed the level of antibodies in 36 patients who were documented as contracting COVID-19 in March 2020. About half of the patients went on to get COVID-19 vaccines, but the rest remained unvaccinated. Samples from all but two were tested at timed intervals, ending in September 2021, using assays that have received clearance from the U.S. Food and Drug Administration.
“At 18 months, 97% participants tested positive for anti-NCP, hinting towards the persistence of infection-induced immunity even for the vaccinated individuals,” researchers wrote in the preprint paper, which was published on the medrxiv website.
NCP stands for nucleocapsid, a part of SARS-CoV-2. Antibodies are believed to protect people against infection from the virus.
“Antibodies against nucleocapsid will be present only in recovered individuals and not vaccinated,” Dr. Asiya Zaidi, a research fellow at the Associazione Naso Sano and one of the authors, told The Epoch Times in an email.
That means even the people who got vaccinated received protection from natural immunity, explained Zachary Stieber of The Epoch Times.
Researchers did find that vaccination with Pfizer-BioNTech COVID-19 vaccines gave those with prior infection a significant boost, but that the increase in protection waned relatively quickly.
“Our study findings demonstrate that while double dose vaccination boosted the IgG titers in recovered individuals 161 times, this “boost” was relatively short-lived. The unvaccinated recovered individuals, in contrast, continued to show a steady decline but detectable antibody levels. We do believe that further studies are required to re-evaluate the timing and dose regimen of vaccines for an adequate immune response in recovered individuals,” Zaidi said according to Mr. Stieber’s reporting.