The BA.5 version of Covid-19 has become the majority variant of the virus in the United States in a matter of weeks, in a worrying development that occurs in the midst of what is perhaps already the second largest wave in America of the United States. pandemic.
It also comes at a time when much of the United States has relaxed almost all of Covid’s restrictions in public and life has returned to normal.
“The Covid-19 is clearly not over. We are seeing dramatic increases in the number of cases and hospitalizations in many parts of the United States,” said Jason Salemi, an associate professor of epidemiology at the College of Public Health. the University of South Florida.
As BA.5, one of Omicron’s sub-variants, begins to hit the U.S., “we’re going in the wrong direction,” Salemi said. “We’ve seen him come for a while … We’ve seen him go pretty non-stop.”
More than one in three Americans live in a medium-risk county in Covid, and one in five has a high risk, according to the U.S. Centers for Disease Control and Prevention (CDC). This is the highest proportion of the country facing risks since February, Salemi said.
There are now more than 100,000 new confirmed cases of Covid in the US every day, a rate that has been fairly steady over the past six weeks. Although cases in the northeast have slowed, waves are now affecting other parts of the country.
There are many opportunities for decreased immunity and decreased vaccine protection, without these booster doses, to allow these new circulating variants with some perhaps more troubling features to do a little more harm to Jason Salemi.
At the same time, hospitalizations have risen steadily since their lowest pandemic fall in April, although the rise has not been as strong or the peak as high as previous waves.
“The older you are, the more likely you are to be hospitalized,” Salemi said. “But hospitalizations are increasing for each age group.”
Hospitalizations tend to lag behind cases a few days. But a seemingly stable rate of cases with an increase in hospitalization means there seems to be something else at stake, experts said: Immunity is likely to decline in the face of a more contagious, immunoevasive and pathogenic variant.
The virus is evolving to circumvent the protection against infection offered by vaccination or recovery from a previous illness with Covid and appears to be more transmissible as well.
The immunoevasive properties of evolving variants make new waves more likely, says Tulio de Oliveira, director of the Center for Epidemic Response and Innovation at Stellenbosch University and leader of the Genomic Surveillance Network in South Africa.
“BA.4 and 5 are potentially the variants that can break immunity more easily,” he said. They are “really capable of reinfecting.”
In South Africa, BA.1, the first variant of omicron, offered very little protection against infection with BA.4 and BA.5, Oliveira said. Antibodies generated by a BA.1 infection do not protect against reinfection after two to three months, according to laboratory research.
There are simple steps we can take to drastically reduce the risks, not just for ourselves and our family, but for many of the members of our community who are very vulnerable, Jason Salemi.
BA.2 infection seemed to offer some protection, possibly because that wave was more recent, he said.
But while immunity to infection appears to be low, previous immunity still resists serious outcomes such as hospitalization and death.
People who have been vaccinated and those who were previously infected “easily acquire BA.4 and BA.5, but will develop very little disease,” de Oliveira said.
In a prepress study on hamsters, the new variants appear much more virulent and pathogenic than the earlier omicron variants. But South Africa saw no more gravity of BA.4 and 5 than during its other omicron waves.
This is because the severity of these variants depends on the levels of immunity in addition to their intrinsic properties. “Now [severity] it is a property not only of the variant itself, but of the variant and of the population with which it is ”, said de Oliveira.
Even before this increase, it was estimated that about 95% of South Africans had protection against vaccination or previous attacks with Covid.
“We believe that this hybrid immunity in South Africa is what kept our BA.4 and BA.5 wave going with very low hospitalizations and deaths,” de Oliveira said.
Even if the variants are more pathogenic in the laboratory, high levels of immunity can help keep serious diseases at bay. That’s why keeping up to date on vaccination is key.
“The first and second reinforcements are very important,” Salemi said.
However, only 34% of eligible Americans, over the age of 5, have received booster doses as recommended by the CDC. Although the absorption of the first reinforcement has been better among the older Americans, the highest risk age group, the intake of the second reinforcement has been extremely low.
“There are many opportunities to decrease immunity and vaccine protection, without these booster doses, to allow these new circulating variants with some perhaps more troubling features to do a little more damage,” Salemi said. Decreased immunity along with a more evasive immune variant means that “you may start to see a reaction in some of these indicators of serious illness.”
Deaths in South Africa also remained low largely because hospitals were not overflowing. “When the BA.4 and BA.5 waves started, we had the ICUs completely empty, so anyone who got sick could have good support,” de Oliveira said.
“This will be key in the US,” he said. “It’s very different if a new wave comes and hospitals are already overflowing.” That’s one of the reasons the Delta wave was so deadly, because it lasted for a long time and kept hospitals full, he said.
Pockets in the U.S. with low levels of immunity, including those that have not recently been vaccinated or have not recovered from the virus, could see a more serious illness. But sites with high vaccination rates and recent increases are likely to do better when it comes to hospitalization and death, he said.
In South Africa, the wave came quickly and also ended quickly, but it had important economic effects as people were unable to work due to illness.
To keep to a minimum the effects of an increase, including the risk of economic disruption and long-term problems like the long Covid, Americans must “lower the numbers as fast as we can,” Salemi said.
This includes taking the same steps that have been shown to help manage the virus in the past: vaccines, masks, distancing, ventilation, testing.
“Please don’t think of mitigation as all or none,” Salemi said. “There are simple steps we can take to drastically reduce risks, not just for ourselves and our family, but for many of the members of our community who are very vulnerable.”
As each infection offers new opportunities for the virus to evolve and escape immunity, scientists and officials around the world must continue to monitor it, de Oliveira said.
“This virus has surprised us too many times.”