SAN FRANCISCO (KGO) -- Doctors say the worst COVID subvariant is here and it comes with more problems that impact all of us.
It's never been easier to get infected with COVID, even if you're vaccinated. The reason, BA.5.
California is never called a red state, but when it comes to COVID transmission the Centers for Disease Control and Prevention couldn't be more clear -- it's nearly all red. According to this map, almost every county across the state - including the entire Bay Area - is red signaling high levels of COVID community transmission.
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"I think it could be our second worst surge in terms of numbers of cases," said UCSF's Dr. Peter Chin-Hong. "We have to be careful."
The CDC estimates more than half of new COVID cases stem from omicron's subvariants BA.4 and BA.5. But, Dr. Chin-Hong explains why the latter is the one to worry about.
RELATED: Omicron subvariants BA.4, BA.5 are spreading 'like wildfire'
"The real superpower of BA.5 is reinfections," said Chin-Hong. "And because BA.5 is new, if you got infected two or three weeks ago, it's not likely BA.5, so you're susceptible to reinfection."
Here are five reasons why BA.5 could be the worst variant yet:
1. Preliminary evidence not yet peer-reviewed from the Kirby Institute suggests false negatives on rapid antigen tests may be higher with BA.5.
U.S. physician and scientist Eric Topol explains.
"It's very common for people to turn positive on day four or five of symptoms if only using a rapid antigen test," said Chin-Hong. "So some tricks are combing the nose and the throat and repeating the tests multiple times."
2. BA.5 is the most transmissible variant out there. According to the CDC, it's at least 20% more infectious than omicron - now tying or surpassing measles, the world's most infectious viral disease. Doctors say this means it will be easier to get - even in environments we consider 'safe' like outside.
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"The more transmissible the virus is the easier it is to get," said UCSF Epidemiologist Dr. George Rutherford. "It's always possible and if you're in crowded outdoor areas, it's very possible."
3. Symptoms of BA.5 are similar to that of previous strains - but early evidence has shown they may be more painful.
"Symptoms may be more painful," said Chin-Hong. "It won't be so serious you'll go to the hospital but it will be very uncomfortable."
Dr. Chin-Hong says anecdotally BA.5 patients are reporting more symptoms of severe sore throat.
"Like their throat is on fire with BA.5," said Chin-Hong. "We hear it's the worst sore throat they've had."
4, 5. Doctors say reason four and five combined could be a problem in the future if transmission continues rise impacting hospital systems. Currently, COVID cases aren't overwhelming hospitals across the Bay Area, but hospitalizations have reached the highest point since February. That paired with a blind spot of COVID cases is causing doctors to caution patients to practice extreme caution. The White House says several hundreds of thousands of new COVID cases are likely underreported each day across the U.S.
RELATED: Undercounted COVID cases leave US with a blind spot as omicron subvariant BA.5 becomes dominant
"About one in 15 people probably have no symptoms but are likely infected. That means if you go into Trader Joe's and 50 people are there, three people are going to be infected and you have no idea," said Chin-Hong.
Could all of this mean additional restrictions like mask mandates may come back?
"As we start to enter the fall when people are coming indoors and schools are back in session, it's on the table, it's always a possibility," said Rutherford.
Currently, masks are strongly recommended indoors and in crowded public settings across the Bay Area. But according to health officials, that could change depending on what we see happen over the next few weeks.
Are we in a surge now?
Not yet, according to Chin-Hong. But he describes it as a 'holding pattern.' He says we should know within two weeks whether a surge is coming. The biggest indicator will be any impact to hospitalizations.
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