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Experts say policies such as mask mandates in Los Angeles County schools have helped California achieve the lowest COVID-19 case rates in the country. ROBYN BECK/AFP via Getty Images
  • California has by far the lowest COVID-19 transmission rate in the country.
  • Experts say the state’s high vaccination rate is the main reason.
  • They add that the state’s strict policies on mask wearing and vaccination requirements at some public events are also factors.

America’s most populous state also has the lowest COVID-19 transmission rate in the country.

The state’s robust vaccination campaign may be the main reason why.

At the moment, California has the lowest per capita rate of COVID-19 cases at 42 per 100,000 residents. It’s currently one of only two states with a case rate of less than 100 per 100,000 (Connecticut is the other).

By comparison, the daily per capita case rate in Alaska — the state with the highest transmission rates this past week — is sitting at 785 per 100,000 people.

The rate in West Virginia, the second highest in the United States, is 652 per 100,000 people.

Nearly 60 percent of California residents are fully vaccinated against COVID-19, compared to about 50 percent of Alaskans and 40 percent of West Virginia residents.

Texas, which is larger than California by area and is the second-most populated state, has a COVID-19 per capita transmission rate of 270 per 100,000 residents and has the most new cases of any state.

“The combination of the vaccine and public health measures really does work and are our way out of this cycle of pandemic,” said Dr. Stephen Parodi, Kaiser Permanente’s national infectious disease lead and clinical lead for Kaiser’s coronavirus response.

California has administered more vaccines than any other state with more than 50 million doses given so far.

Jeanne S. Ringel, PhD, an economist, health policy analyst, and director of the Access and Delivery Program at the RAND Corporation, told Healthline that it’s difficult to pinpoint which of California’s myriad of COVID-19 prevention efforts or demographic, cultural, or even geographic factors are responsible for the state’s success in keeping transmission rates low, even as the Delta variant spreads across the country.

“I think the high vaccination rates is a big driver, but it can’t be that all alone,” Ringel said.

According to state health officials, California has prioritized vaccination, including deploying a variety of mobile resources to target the state’s unvaccinated populations.

California health officials point out that the state has:

  • issued public health orders recommending indoor mask wearing
  • required vaccine verification for attendees of large indoor events (and recommended them for outdoor mega events)
  • issued vaccine requirements for healthcare workers, state employees, and visitors at healthcare facilities
  • required vaccine verification or testing for school workers

Ringel said that California’s vaccine and testing mandates also likely play a role in lowering transmission of COVID-19.

“There may be more compliance with public health recommendations here than in other places,” she added.

Outreach efforts to target under-vaccinated populations in the state are also aided by California’s detailed information on vaccination rates.

“Groups that are out providing vaccination in communities have the data they need to best target their resources,” said Ringel.

Parodi told Healthline that vaccination rates vary widely by community in California.

“We have locales approaching 90 percent of the eligible population and other parts of the state that are closer to 50 or 60 percent,” he said.

California has excelled at creating good COVID-19 partnerships among public and private healthcare companies such as Kaiser Permanente, said Parodi, with involvement of statewide organizations like the California Medical Association and the California Hospital Association.

“The outreach efforts are really key here,” Parodi said, with efforts aimed at the Latinx, Black, and rural communities using culturally and linguistically appropriate materials and trusted advisors and local leaders to encourage vaccination.

In some areas, the message is delivered by members of the faith community. In others, local doctors have taken part in public forums.

Testimonials by individuals who have changed their mind in favor of getting vaccinated — often due to personal experience with COVID-19 — also have been effective, said Parodi.

“This is a real endorsement of public health measures working,” Parodi said.

He noted that high vaccination rates in regions such as the San Francisco Bay Area have corresponded to hospitalization rates up to 70 percent lower than in less-vaccinated communities.

“Even with Delta, we don’t have to be resigned to having more hospitalizations if large proportions of the population get vaccinated,” Parodi said.