Are the Subvariants of SARS-Cov-2 Virus Accelerating the Pandemic?

A new study has uncovered why COVID-19 subvariants spread rapidly and how antiviral treatment with Paxlovid have made individuals more susceptible to future infections. “There were real concerns about new waves of cases driven by BA.5, //which had replaced BA.2.12.1 as the dominant strain in the United States,” said Aaron Carlin, MD, PhD, associate professor of pathology at University of California San Diego School of Medicine. “It looks like past infection by an earlier subvariant would not elicit cross-protection against the new BA.4 and BA.5 subvariants.”

COVID-19 Statistics

• The pandemic killed nearly 7 million people worldwide
• In the United States, COVID-19 vaccination prevented more than 18 million additional hospitalizations

The researchers found that mutations in the spike protein of BA.4 and BA.5 allowed it to evade neutralizing antibodies generated by vaccination or by an earlier SARS-CoV-2 infection. Moreover, they determined that early treatment with Paxlovid, an oral antiviral pill that combines drugs (nirmatrelvir and ritonavir), dampened the natural development of antibodies, leaving people with lower overall immune responses and perhaps more vulnerable to subsequent infection.

Paxlovid was among the first drugs developed and tested to treat COVID-19, and quickly became a go-to medication, often prescribed when symptoms first appeared and intended to reduce the likelihood of severe disease, hospitalization or death.

Paxlovid Treatment for COVID-19

But Paxlovid proved poor insurance against recurrence of COVID-19 or subsequent re-infection.

In June 2022, senior author Davey Smith, MD, chief of Infectious Diseases and Global Public Health at UC San Diego School of Medicine and an infectious disease specialist at UC San Diego Health, Carlin and colleagues published data suggesting the so-called “Paxlovid rebound” was likely due to insufficient drug exposure.

In October 2022, Smith and colleagues published a different study that documented the likelihood of COVID-19 symptoms recurring in untreated patients after initial symptoms had disappeared.

“The findings also highlight the importance of ongoing research and the need for continued efforts to understand the virus and develop effective treatments and vaccines. The past is prologue, not because the virus is the same, but because it is constantly changing, so we must evolve as well to meet the threat and anticipate the next pandemic.”

Co-authors include: Alex E. Clark, Aaron F. Garretson, William Bray, Magali Porrachia, Tariq M. Rana and Antoine Chaillon, all at UC San Diego; and AsherLev T. Santos, CSU San Marcos.

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Source-Eurekalert