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Vaccine ‘Breakthroughs’ Mean Widespread COVID-19 Testing Must Continue

Widespread testing for the SARS-CoV-2 virus will have to continue for the foreseeable future, according to a new study. The reason? Breakthrough COVID-19 infections in fully vaccinated people, possibly by virus variants. While those are rare, the authors point out, they cast a spotlight on the need to make sure cases don’t spread. Here is more information.

NEW YORK – Breakthrough infections after full COVID-19 vaccination don’t indicate that the vaccines are ineffective. Quite the contrary, according to a new study, but the possibility of infections from emerging variants in fully vaccinated people – no matter how rare – argue that other precautions should continue.

Rockefeller University researchers identified 2 women with vaccine breakthrough infection in a cohort of 417 individuals who had received the second dose of BNT162b2 (Pfizer–BioNTech) or mRNA-1273 (Moderna) vaccine at least 2 weeks previously.

“Despite evidence of vaccine efficacy in both women, symptoms of coronavirus disease 2019 developed, and they tested positive for SARS-CoV-2 by polymerase-chain-reaction testing,” the study team wrote in a report in the New England Journal of Medicine. “Viral sequencing revealed variants of likely clinical importance, including E484K in 1 woman and three mutations (T95I, del142–144, and D614G) in both. These observations indicate a potential risk of illness after successful vaccination and subsequent infection with variant virus, and they provide support for continued efforts to prevent and diagnose infection and to characterize variants in vaccinated persons.”

The authors raise concern that the emergence of viral variants, particularly in the S gene, threaten vaccines’ continued efficacy and “provided an impetus to increase testing and sequencing of viral DNA in infected persons in order to understand the transmissibility, virulence, and ability of variants to evade current vaccines.”

The report notes that New York City has seen a disturbing increase in viral variants; in fact, the B.1.1.7 variant first identified in the United Kingdom and the B.1.526 variant first identified in New York accounted for more than 72% of new cases as of March 30, 2021.

According to the study, the observations bolster concerns about a small but ongoing risk among vaccinated individuals, and the possibility that they can continue to spread the virus.

“These patients got vaccinated, had great immune responses, and nonetheless broke through with a clinical infection,” pointed out co-lead researcher Robert B. Darnell, MD, PhD. “The idea that we could be entirely done with testing in the post-vaccine world is probably not a good one right now; for example, even fully vaccinated people who develop respiratory symptoms should consider getting tested for COVID-19. “Conversely, exposure to individuals with known infection, even if fully vaccinated, should be taken seriously and again individuals should consider getting tested."

A lot of the issue comes down to numbers and percentages, according to the study. "Given the scope of the pandemic, there's a huge amount of virus in the world right now, meaning a huge opportunity for mutations to develop and spread," Darnell added. "That is going to be a challenge for the developers of vaccines over the next months and years."

The best response, according to researchers, is to “maintain layers of mitigation strategies, including serial testing of asymptomatic persons, open publication and analysis of vaccination and infection databases (such as those accruing data in New York City), and rapid sequencing of SARS-CoV-2 RNA obtained from a variety of high-risk persons.”