The most contagious version of COVID yet has arrived in California. Will it bring a new pandemic surge?
Californians may soon mask in public places again, as the BA.5 COVID variant sweeps the state. Santa Clara Valley Transportation Authority / Wikimedia Commons California Public Records Act
Four months after Gov. Gavin Newsom announced that California was taking a new approach to dealing with the COVID pandemic, shifting away from a focus on preventing the spread of the disease to treating the virus as a fact of life, the state is facing a potential surge caused by a new variant. BA.5 is a variant of Omicron, which itself was a variant of the original COVID virus that first appeared in late 2019.
Along with its similar predecessor, BA.4, the new version of the virus is responsible for more than 52 percent of all new COVID infections in the United States. In the last week of June, the two variants accounted for 37.4 percent.
Why the sudden spike? The alarming answer is that BA.5 is not only the most contagious COVID variant yet seen, it may be the most contagious virus of any kind, ever.
Not only does BA.5 appear to be more infectious than measles, the previous record-holder, this new version of COVID is approximately nine times as contagious as the common cold.
The contagiousness of a virus is measured by a number referred to as R0, which is spoken as “R-naught.” The R0 number, also called the “reproduction rate,” is a measure of how many people are likely to catch a virus from a single infected person. For the original strain of the COVID virus, the reproduction rate was 3.28. In other words, a single infected person could expect to cause slightly more than three other people to get sick.
How Contagious is the New Variant?
Rhinovirus, which causes the common cold, has an R0 number of 1.88. Influenza is roughly similar at 1.68. Measles has an R0 usually measured between 12 and 18.
Early studies indicate that the reproduction rate for BA.5 is 18.6.
The safest place for avoiding COVID infections has long been considered to be outdoors in open air. But BA.5 and BA.4 may be changing even that calculation, simply because they are so highly transmissible that catching the virus outdoors becomes more likely, especially in large groups of people.
“Being at parks and outdoor sporting events is still what we should turn to,” Stanford University infectious disease specialist Dr. Anne Liu told the San Francisco Chronicle. “But if you are in a dense crowd or in an outdoor space that has been modified to look like an indoor space, then the risk becomes higher.”
Just a few months into its new strategy of treating COVID as “endemic,” is California ready for a BA.5-driven surge?
I’m Fully Vaccinated. Why Should I Worry?
As with all previous COVID variants, being vaccinated—especially with at least one booster shot—offers far better protection than going unvaccinated, particularly against COVID so severe it causes hospitalization or even death. But when it comes to simply catching the disease, BA.5 and BA.4 seem to be better than any previous variants at getting past the immunity built up by vaccination. The same goes for previous infections, which also appear to be much less effective and staving off future infections from the new variants.
The original Omicron variant, as well as its initial subvariants BA.1 and BA.2, were first detected in South Africa. That country experienced the first Omicron wave, but after that period saw little impact from the first two BA strains, leading scientists to conclude that the danger of getting a second COVID infection after enduring a case of Omicron was low.
But BA.4 and BA.5 are a different story. Despite a 90 percent immunity rate due to previous infection and vaccination, South Africa saw its COVID case rate triple during late April and early May. The only possible reason was that the new variants, BA.4 and BA.5, were much more capable of causing new infections in people with “immunity.”
Wearing a mask over the nose and mouth remains an effective way to guard against transmission of the virus. But as part of the state’s new approach, California no longer requires mask-wearing in public spaces, at least for vaccinated people. (Unvaccinated people are mostly on the honor system.) But businesses can still require masks for their employees and customers if they choose, and no one may be prevented from wearing a mask.
Are the New Variants Affecting California?
Counting COVID case numbers accurately has become much more difficult than in earlier stages of the pandemic, largely due to the increased popularity of at-home testing kits, the results of which are supposed to be reported to public health authorities but usually aren’t. Hospitalizations and deaths from COVID, however, remain indicators of surges and lulls in spread of the virus. And in California, those numbers are up.
According to the Los Angeles Times COVID tracker, as of July 5, COVID hospitalizations in the state were up 26 percent over the prior two weeks than two weeks earlier. Deaths were up more than 20 percent in the same time frame. While the Times recorded cases by variant, it did not break the count down to the level of subvariants. But the Omicron variant, according to the Times statistics, is the cause of 99.1 percent of new cases
The good news is, that even with the increased numbers, hospitalizations and deaths from COVID remain at lower levels than during previous surges. In the Bay Area, according to stats compiled by the San Francisco Chronicle, though the number of COVID patients in hospital intensive care units doubled during the month of May, the region still had ICU beds available.
By the beginning of July, the number of confirmed COVID ICU patients was still significantly lower than during the state’s four earlier surges going back to March of 2021, according to the Chronicle data.
The relatively moderate levels of severe disease—at least as of early July–may be the result of the nature of BA.5 itself which based on data from the recent surge in South Africa does not appear to be especially deadly. South Africa saw little rise in its death toll, despite the surge in cases and increase in hospitalizations.
In California, a statewide vaccination rate of over 75 percent for residents ages five years old and up may also be a reason why the surge in BA.5 has not yet caused high levels of severe disease and death. More than half of all eligible Californians, 58 percent, have received at least one booster shot of a COVID vaccine as well, according to state public health data.
