A highly mutated COVID-19 strain is circulating in California \u2014 raising concerns that disease activity could rise heading into the summer. <\/p>\n
The emergence of the BA.3.2 strain, nicknamed \u201cCicada,\u201d comes amid broader uneasiness about COVID vaccination rates among seniors \u2014 who are especially susceptible to the virus \u2014 and whether complacency after back-to-back relatively quiet winters<\/a> has left the elderly vulnerable. The \u201cCicada\u201d nickname refers to this subvariant\u2019s apparent dormancy before it reemerged in 2025, akin to some periodically active insects<\/a> of the same name. <\/p>\n The timing of the spread of the Cicada subvariant also underscores that COVID has lately morphed into more of a summer disease in California. In fact, the summer peaks of COVID in 2024 and 2025 were worse than their<\/a> respective winter peaks, according to the California Department of Public Health \u2014 a stark departure from the earlier years of the pandemic, when winter surges ripped through California with devastating regularity.<\/p>\n Instead it was the flu that was the dominant respiratory virus<\/a> the last two winters, with this past season considered moderately severe. <\/p>\n \u201cThis Cicada variant may be increasing just in time for what for COVID is more of a summer hit,\u201d said Dr. Neil Silverman, director of the Infections in Pregnancy Program at the David Geffen School of Medicine at UCLA. \u201cCOVID doesn\u2019t seem to play by the same rules that influenza tends to play by, where its cycle is predictable.\u201d<\/p>\n Dr. Peter Chin-Hong, a UC San Francisco infectious diseases expert, said Cicada is \u201ca different kind of variant that\u2019s increasing. It looks so different from the other ones that have been circling since JN.1<\/a> came on board\u201d in late 2023. <\/p>\n \u201cMy ears are perking up,\u201d he said. <\/p>\n In lab studies, the Cicada subvariant efficiently evades immunity from a prior vaccination or infection, according to a report published by the U.S. Centers for Disease Control and Prevention. That raises the possibility of a seasonal increase in COVID-19, the researchers said<\/a>.<\/p>\n \u201cAlthough widespread infection- and vaccine-conferred immunity have decreased rates of severe COVID-19 over time, the public health impact of COVID-19 is still considerable,\u201d scientists recently wrote in the CDC\u2019s Morbidity and Mortality Weekly Report. <\/p>\n During the 2024-25 respiratory virus season, there were an estimated 45,000 to 64,000 COVID deaths and 390,000 to 550,000 hospitalizations. <\/p>\n A potential uptick is concerning as recent COVID vaccine coverage remains scant \u2014 even among the most vulnerable Californians. Statewide, just 28.7% of seniors age 65 and up have received at least one dose of the COVID vaccine that was updated in September. <\/p>\n The California Department of Public Health recommends<\/a> that everyone ages 6 months and up should have access to the vaccine, and that those at higher risk of severe illness should get immunized \u2014 including older adults, pregnant women and infants and toddlers. The same goes for healthcare workers, residents of long-term care facilities and people who have household members at high risk. <\/p>\n People at higher risk for COVID-19, including seniors and those who are immunocompromised, should get two doses of the updated COVID-19 vaccination, spaced six months apart, state health officials said in a briefing to health professionals. <\/p>\n \u201cTo me, the biggest threat … is the low vaccination rate in seniors,\u201d Chin-Hong said. \u201cThe landscape of divisiveness around vaccines is leading people to be confused and to think of COVID as being political when it\u2019s not.\u201d <\/p>\n The Cicada subvariant was initially detected in South Africa in November 2024, and first found in the U.S. in a sample given at San Francisco International Airport in June 2025 by an international traveler from the Netherlands.<\/p>\n By that September, detection of the subvariant was increasing. In November, BA.3.2 was identified in a wastewater sample in Rhode Island; and among patients, the first detections of the new subvariant were found in three different states in December and early January. <\/p>\n As of February, the Cicada subvariant has been reported in 23 countries, and has also been seen among airline passengers to the U.S. traveling from the United Kingdom, Japan and Kenya. Over the autumn and winter, about 30% of coronavirus samples analyzed in three European countries \u2014 Germany, the Netherlands and Denmark \u2014 were the Cicada subvariant, according to the Morbidity and Mortality Weekly Report. <\/p>\n It\u2019s not a surefire bet the Cicada subvariant will bring a summer of misery, however. COVID wasn\u2019t appreciably worse this past winter than in previous years in central Europe. <\/p>\n According to the California Department of Public Health, the Cicada subvariant remains at low levels in the state\u2019s wastewater, and there have been no reports of increased severity of illness among those who were infected. It\u2019s also not projected to be a particularly fast-growing subvariant, nor a dominant one. <\/p>\n The last time the Cicada subvariant was detected in one public database, it represented about 5% of samples identified in U.S. wastewater for the week of March 28, according to Alexandria Boehm, professor of civil and environmental engineering at Stanford University and principal investigator of WastewaterSCAN, which monitors sewage to track the presence of infectious diseases.<\/p>\n During the first week of April, though, the Cicada subvariant was not detected, and all the samples were of another COVID strain, XFG, according to Boehm. <\/p>\n It\u2019s notable that concentrations of the coronavirus in wastewater have been relatively low and, as a result, \u201cit is hard to obtain high-quality, high-confidence sequences,\u201d Boehm said. <\/p>\n In slides prepared for a recent briefing of medical professionals, California health officials forecast a potential modest wave of COVID in the late summer and early fall. <\/p>\n Chin-Hong likened it to a weather report. <\/p>\n \u201cThe clouds are coming, and you might get a downpour, or it might just pass on. We don\u2019t really know, but it just gives us some pause,\u201d he said. <\/p>\n Chin-Hong urged seniors who haven\u2019t gotten the COVID vaccine in the last 12 months to do so. \u201cGetting it once a year as a senior is going to be really important,\u201d he said. <\/p>\n Data continue to show that the COVID vaccines are safe and effective, and protect both pregnant women \u2014 who are susceptible to more severe disease should they get infected \u2014 and their newborns, Silverman said. Of infants up to 6 months of age who were hospitalized with COVID, nearly 90% were born to women who had no record of vaccination against COVID during pregnancy, according to a report published<\/a> by the CDC. <\/p>\n