New COVID variants arrive ‘out of the blue,’ likely reinfecting omicron survivors

A couple of new omicron sub-variants have emerged, raising the possibility that survivors of earlier omicron strains could be re-infected.

BA.4 and BA.5 have gained increasing attention in South Africa as weekly coronavirus cases tripled in the past two weeks, according to data from Johns Hopkins University.

“It really came out of nowhere over the weekend. We were already settling with BA.2.12.1, and then BA.4 and BA.5? said Dr. Peter Chin-Hong, an infectious disease expert at UC San Francisco. “It just feels like the latest chapter in a never-ending saga.”

The rapid growth of BA.4 and BA.5 in South Africa has implications for a possible future increase in California and the US is unlikely to be re-infected with the even more infectious BA.2 subvariant, which is now dominant in the whole country.

But the rise in cases in South Africa of BA.4 and BA.5 follows an earlier wave of omicron. It is estimated that 90% of the South African population is immune to the above omicron variants, either by surviving natural infection or by vaccination.

“If 90% of people are already immune and seeing an increase in cases, it means that this particular dynamic duo [BA.4 and BA.5] they are causing more reinfections, even in people who already had omicron,” Chin-Hong said.

Only a small number of cases of BA.4 and BA.5 have been documented in California. In April, one case of BA.5 was documented and one case of BA.4 was confirmed in March, according to the California Department of Public Health.

The omicron subvariant BA.2 remains the dominant variant in California, accounting for 88% of the nearly 3,600 cases analyzed in April, while the ascendant BA.2.12.1 and its relative, BA.2.12, accounted for 9% of the cases. cases.

BA.2.12.1 is estimated to be 25% more transmissible than BA.2.

Will BA.4 and BA.5 lead to another wave in the US?

Some health experts say the BA.4/BA.5 wave from South Africa could repeat itself in the US, but probably not right away.

South Africa will start its winter next month, while summer approaches for the US.

But will the South African experience herald a late summer or fall surge in the US, as Americans’ immunity to a natural omicron infection or their latest vaccine wanes? Perhaps, but “we don’t know,” Chin-Hong said.

Current data does not suggest that BA.4 and BA.5 make people sicker than earlier omicron variants. But BA.4 and BA.5 appear to be more transmissible, Chin-Hong said, and more likely to evade existing immunity, given the surge in South Africa.

People who are not vaccinated and who have not been previously exposed to the coronavirus will have a higher chance of not being well if they are infected, Chin-Hong said.

The emergence of BA.4 and BA.5 means that “omicron is still alive and well, and looking for ways in which it can evolve to be even more transmissible,” said Dr. Robert Kim-Farley, an epidemiologist and infectious disease expert. . with the UCLA Fielding School of Public Health.

Fortunately, the data available so far does not suggest that the coronavirus is evolving to give infected people a higher chance of hospitalization or death.

Still, people need to know where the pandemic is headed in their own communities, Kim-Farley said. When transmission is high, as it is in Los Angeles County, it’s time to be more vigilant about wearing masks in crowded indoor settings, she said.

And people who are at higher risk of severe illness and death from COVID-19 may want to avoid risky situations altogether, Kim-Farley said.

Chin-Hong said it’s important for people to know ways to reduce risk. In addition to keeping up with vaccinations and booster shots and wearing a mask in closed public places, people can also reduce risk by learning where to get Paxlovid, an anti-COVID pill that can reduce the risk of hospitalization by 90% .

For people who are immunocompromised, Evusheld is available to prevent COVID-19 among people who have not been exposed to the coronavirus and have a weakened immune system due to a medical condition or cannot be vaccinated for medical reasons.

Kim-Farley said there is likely to be a spike in cases over the summer in California. “However, I am optimistic that we will not see this translate into high levels of hospitalizations or deaths, just because the variants that are emerging appear to be more transmissible but cause less serious illness and death.”

The most worrisome wild card would be an entirely new variant that is more likely to cause serious illness and death, and against which vaccines and natural immunity would be less effective.

“The important message for everyone is to still get vaccinated and if you are eligible, get boosted because these are life-saving vaccines,” Kim-Farley said.

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