At least 39 Sonoma County residents tested positive for the COVID-19 virus even after getting their coronavirus vaccines, county health officials said in a statement on Tuesday.

Currently, Sonoma is the only county in the Bay Area that has recorded positive tests from people who have been inoculated with the new vaccines. However, experts are anticipating similar experiences with other regions in the coming weeks.

Re-infection After Vaccination

“This result is not unexpected. We know that the various vaccines are not 100% effective,” county spokesperson Matt Brown said.

The recent development involved 1% of total positive cases observed in the last four months, county officials said. “We expect this rate to be present in other counties as well,” said Brown.

Officials conducted contact tracing of the infected individuals and determined they did not infect anyone else. Additionally, only one of the 39 people involved was brought to the hospital after showing signs of moderate illness for a short period.

“We’ve been monitoring the contacts of these people that have tested positive (after vaccinations) and there doesn’t seem to be any transmission from these folks, these breakthrough cases, to subsequent contacts. That’s really the most important message, besides not having any severe outcomes,” county epidemiologist Jenny Mercado said.

None of the three currently authorized coronavirus vaccines in the United States; Johnson & Johnson, Moderna, and Pfizer, give 100% protection from the COVID-19 virus. Public health officials said “breakthrough cases” could happen soon where a vaccinated individual is infected with the virus.

“We absolutely expect this to happen with these outstanding mRNA vaccines. We know that it’s not going to happen in 90% to 95% of people who get vaccinated, which means it’s going to happen in 10% to 5%. It’s anticipated we will see this,” Dr John Swartzberg said. Experts also observed that people who got the vaccine are likely to develop only mild symptoms or are asymptomatic, the San Francisco Gate reported.

Swartzberg told the public that the news was a reminder to keep wearing face masks and practice social distancing. He added it was a motivation to continue driving away the coronavirus from our communities. “We have to get community control,” he said.