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And according to Fyodor Kondrashov, an evolutionary geneticist at the Institute of Science and Technology Austria in Klosterneuburg, it should also help keep the emergence of vaccine-resistant variants at bay. Getting more people vaccinated is the single most effective intervention to keep transmission rates low, but any bump in vaccine effectiveness can help as well. So far, no human vaccine has been completely undermined by resistance in the way that many anti-infective drugs have, says Andrew Read, who studies the evolution of infectious diseases at Pennsylvania State University in University Park.

The Delta variant took the world by surprise. Evolution — and our immunological responses — could have more surprises in store. COVID boosters for wealthy nations spark outrage. But any discussion around the need for boosters cannot be had in a vacuum. In addition to considerations of immune kinetics among the immunized, there are also issues of vaccine equity and availability to factor in.

And as long as vaccinated people are staying out of hospitals and morgues, then to Katrina Lythgoe, an evolutionary epidemiologist at the University of Oxford, UK, theoretical arguments around vaccine resistance are secondary. Khoury, D. Nature Med. PubMed Article Google Scholar. Naaber, P. Lancet Reg. Health Eur. Article Google Scholar. Thomas, S. Pegu, A. Science , — Goel, R. Turner, J. Nature , — Goldberg, Y. Bar-On, Y.

Chemaitelly, H. Puranik, A. Rella, S. Download references. Career Guide 10 NOV News 08 NOV Testing positive for COVID even without symptoms can be disruptive, but how long should we expect to test positive for? This is a question that millions of us have asked ourselves, and with good reason.

It means we have to limit contact with members of our household, isolate for several days, thus withdrawing again from daily activities, and disrupt travel plans. After nearly two years of the COVID pandemic, life being thrown into constant chaos can feel exhausting. The time taken to test negative after contracting COVID depends on the severity of the case, and also on the test itself. PCR tests that hunt out parts of viral genetic material RNA in the case of COVID in our bodies and amplify it so we can detect it are extremely sensitive and can even pick up the presence of few viral fragments.

But there are still nagging questions about how long protection from the coronavirus vaccines will last. For instance, will your shot wear off gradually or suddenly?

Will you need a booster? Vaccine longevity became a hot topic in August, when some studies began to suggest vaccine effectiveness was waning, although data also showed the vaccines were still highly effective against hospitalization. Pfizer and Moderna have been monitoring immunity in people who were given their vaccines in the initial clinical trials—both companies had reported strong overall efficacy at the six-month mark.

Pfizer reported on its efficacy in a preprint that has not been reviewed by outside scientists; Moderna released a company statement. A report in The New England Journal of Medicine NEJM in April showed that 33 participants who had received the Moderna vaccine during the Phase I trial had a gradual decline in antibody protection—and, based on the slope, Iwasaki says, that is hopeful news.

It should be noted that the trial occurred prior to Delta becoming the predominant virus variant.