Vaccination is not enough by itself, study finds

Vaccination alone won't stop the rise of new variants and could push the evolution of strains that evade their protection, researchers have warned. The researchers, from Austria, Spain and Switzerland, said people need to wear masks and take other steps to prevent spread until almost everyone in a population has been vaccinated.

In findings published in Nature Scientific Reports, they wrote: "We found that a fast rate of vaccination decreases the probability of emergence of a resistant strain. Counterintuitively, when a relaxation of non-pharmaceutical interventions happened at a time when most individuals of the population have already been vaccinated, the probability of emergence of a resistant strain was greatly increased. Our results suggest that policymakers and individuals should consider maintaining non-pharmaceutical interventions and transmission-reducing behaviours throughout the entire vaccination period.”

Study co-author Simon Rella of the Institute of Science and Technology Austria, said: “When most people are vaccinated, the vaccine-resistant strain has an advantage over the original strain. This means the vaccine resistant strain spreads through the population faster at a time when most people are vaccinated.” But if the non-pharmaceutical interventions are maintained - such as mask use and social distancing - the virus is less likely to spread and change. The findings indicate policymakers should resist the temptation to lift restrictions, the authors say.

Read more: Simon A Rella, et al Rates of SARS-CoV-2 transmission and vaccination impact the fate of vaccine-resistant strains, [Open Access] Scientific Reports, volume 11, Article number: 15729, 2021.   CNN News.

USA: COVID cases more than double those reported, experts say

Sixty per cent of COVID-19 cases in the US could have gone unreported due to biases in test data and delayed reporting, a study by researchers at the University of Washington has found. The modelling study published in the Proceedings of the National Academy of Sciences (PNAS) used multiple data sources to estimate the true number of coronavirus infections for one year starting in March 2020. The model included likelihood components that combine data on COVID-19 deaths, confirmed cases, and the number of tests administered each day. The authors concluded continued ‘mitigations’ were required alongside vaccination programmes.

Senior author Adrian Raftery said, “What we wanted to do is to develop a framework that corrects the flaws in multiple data sources and draws on their strengths to give us an idea of COVID-19's prevalence in a region, a state or the country as a whole.” About 65 million US residents (19.7 per cent) ‘likely’ had COVID-19 by 7 March 2021, the model shows. Until that point, only about 1 of every 2.3 infections had been confirmed, suggesting that about 60 per cent of all infections had been unreported.

“Our results indicate that a large majority of COVID infections go unreported,” the authors note. “Even so, we find that the United States was still far from reaching herd immunity to the virus in early March 2021 from infections alone. This suggests that continued mitigation and an aggressive vaccination effort are necessary to surpass the herd-immunity threshold without incurring many more deaths due to the disease.”

Read more: Nicholas J Irons and Adrian E Raftery. Estimating SARS-CoV-2 infections from deaths, confirmed cases, tests, and random surveys, [Full article] Proceedings of the National Academy of Sciences, volume 118 (31), e2103272118, August 2021.  DOI: 10.1073/pnas.2103272118  University of Washington news release. CIDRAP news releaseSource: Risks 1008 

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