Universal vaccine needed to prevent future waves of COVID-19, study finds

Newswise – Their findings underscore the need for more proactive planning and preparedness for future variants of concern (COVs), including the development of a universal vaccine that can block SARS-CoV-2 infection and prevent serious illnesses.

As in many places, by February 2022 South Africa had experienced four separate pandemic waves caused by the original (or ancestral) SARS-CoV-2 virus and three COVs – Beta, Delta and Omicron.

“These repeated pandemic waves were caused by new COVs that erode previous immunity to infection or vaccination, increase transmissibility, or a combination of the two,” says study author Wan Yang, assistant professor of epidemiology at Columbia University Mailman School of Public Health, New York, USA. “Although laboratory and field studies provide information on different epidemiological characteristics, it is difficult to quantify the extent of immune erosion and changes in transmissibility for each VOC.”

To better understand the characteristics of the different COVs of COVID-19, the team developed a mathematical model using weekly case and death data from nine South African provinces, from March 2020 to the end of February 2022, to reconstruct the dynamics of transmission of SARS-CoV-2.

They validated their model using three independent datasets and found that the estimated cumulative infection rates roughly matched the serological data over time, and that the estimated number of infections matched the number of hospitalizations for the four pandemic waves caused by the ancestral, beta, delta and Omicron variants. . The modeled infection numbers also matched the ancestral, beta, and delta wave death rates, but less so for Omicron, because at this point infection and previous vaccinations reduced the number of infected people with fatal outcomes.

Using data that emerged at the time of the new variants, Delta and Omicron, the model was also able to retrospectively predict Delta and Omicron waves before the observed peak in real-life cases and deaths caused by these VOCs. The team found that the model accurately predicted the remaining trajectories of cases and deaths in most of the nine provinces.

After validating their model, they then used it to estimate the epidemiological characteristics of each COV, including infection detection rates, infection fatality rates, population susceptibility and transmissibility, and compared these dynamics between provinces. These “model inference estimates” were then used to quantify immune erosion and increased transmissibility for each COV.

They found that the beta variant eroded immunity in about 65% of people previously infected with ancestral SARS-CoV-2 and was 35% more transmissible than the original virus. This finding was supported by the experience of previously infected participants in one of the vaccine trials, who had similar sensitivity to the beta variant as those without previous infection.

Estimates for Delta varied from province to province, but overall the variant eroded immunity to previous infection or vaccination by about 25% and was 50% more transmissible. This corresponds to a 27.5% reinfection rate reported during the Delta wave in Delhi, India.

Finally, for Omicron, estimates varied but consistently highlighted its known higher transmissibility than previous VOCs. The authors estimated that Omicron was approximately 95% more transmissible than ancestral SARS-CoV-2 and eroded immunity by 55% (prior infections and vaccinations).

These results illustrate that prior high immunity against SARS-CoV-2 does not prevent new outbreaks of COVID-19, as neither prior infection nor current vaccination completely blocks infection with a new variant.

Several concerning and interesting SARS-CoV-2 variants have emerged in the two years since the start of the pandemic, and it is difficult to predict the frequency and direction of future viral mutations, especially erosion levels. immune system, changes in transmissibility and inborn diseases. gravity, say Yang and co-author Jeffrey Shaman, professor and director of the climate and health program at Columbia University Mailman School of Public Health. They add that so far COVs, with the exception of Alpha, have produced some degree of immune erosion, and later COVs like Delta and Omicron are more genetically distinct from earlier variants, making them more capable of causing reinfection despite various previous exposures and vaccinations. Given this pattern, the authors suggest that a universal vaccine capable of blocking SARS-CoV-2 infection and preventing severe disease is urgently needed.

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Universal vaccine needed to prevent future waves of COVID-19, study finds

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