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While the Delta variant surely has played a role in the resurgence of COVID-19 in recent months, these findings suggest that waning immunity also is an important factor. The researchers report that the number of severe COVID-19 cases among the younger fully vaccinated groups were too small to draw any conclusions.
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The rate of severe illness dropped to 0.26 cases per 1,000 among those vaccinated in February and 0.15 cases per 1,000 for those vaccinated in March. The rate of severe COVID-19 among adults 60 years of age or older who were fully vaccinated in January was 0.34 cases per 1,000 persons. And, again, the data show a similar pattern of waning immunity. While such cases were much less common, more than 400 of those with confirmed COVID-19 breakthroughs went on to develop severe illness. The data revealed a similar pattern in those aged 40 to 59 and those aged 16 to 39.Īn important question is whether these breakthrough infections were serious enough to require hospitalization. Those who were vaccinated in February and March had lower infection rates of 2.2 per 1,000 and 1.7 per 1,000, respectively. Among individuals 60 years or older who were fully vaccinated last January, the number of confirmed breakthrough infections was 3.3 per 1,000 people during the three weeks of the study. The results were clear: the rate of confirmed COVID-19 infection revealed a slow but steady waning of immunity over time. Without any significant waning of immunity, one shouldn’t see any difference in infection rates among people who were fully vaccinated at the earliest opportunity versus those vaccinated later. The researchers looked for an association between the rate of confirmed infections and the time that had passed since vaccination. To find out, the researchers looked to over 4.7 million fully vaccinated Israeli adults, more than 13,000 of whom had breakthrough infections from July 11 to 31, 2021 with SARS-CoV-2. Or, they wondered, did the waning of immunity over time also play a role? Researchers led by Yair Goldberg, Technion-Israel Institute of Technology, Haifa, wondered whether this resurgence of COVID-19 could be fully explained by the rise of the more infectious Delta variant. The vast majority of those cases in June-98 percent-were caused by the emerging Delta variant. The rise also included a substantial number of breakthrough infections in vaccinated individuals. By May 2021, Israel had extremely small numbers of confirmed COVID-19 cases-just a few dozen per day.īut the numbers crept back up in June 2021. More than half of adult Israelis received two doses of the Pfizer vaccine within the first three months of the campaign. The study is yet another highly informative report from Israel, where public health officials launched a particularly vigorous national vaccination campaign in December 2020. It found that vaccine-induced immunity, while still quite protective against infection and severe illness from COVID-19, can wane after several months. One of the main studies providing the evidence for CDC’s recommendation was recently published in the New England Journal of Medicine.
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That’s why the Centers for Disease Control and Prevention (CDC) recommends booster shots for several at-risk groups, including folks 65 years and older, those with underlying medical conditions, and people whose occupations place them at high risk of exposure. Though relatively uncommon, breakthrough infections are possible. That will make it safer to spend time with friends and family, though everyone should remain vigilant just to be on the safe side. The winter holidays are approaching, and among the many things to be grateful for this year is that nearly 200 million Americans are fully vaccinated for COVID-19. Francis Collins Credit: bbernard/Shutterstock Israeli Study Shows How COVID-19 Immunity Wanes over Time