Children COVID-19 Vaccine
Maddy Yoo, 12, is inoculated with Pfizer’s vaccine against COVID-19 on May 11, 2021. REUTERS/Chris Aluka Berry

More than 140,000 San Diegans who have received their first dose of the Pfizer or Moderna COVID-19 vaccine are overdue for their second dose, the Health and Human Services Agency reported Thursday.

The report comes as the highly infectious “delta” variant of coronavirus is spreading rapidly in the United States. This variant appears to cause a more severe case of the disease among younger people than other variants.

County health officials said a single dose of either the Pfizer or Moderna vaccine is significantly less effective at protecting people from getting sick, especially against the delta strain.

The recommended spacing of doses is three weeks for the Pfizer vaccine and four weeks for Moderna. But completing the full two-dose series of the vaccine is recommended regardless of how long ago a person received the first shot.

“A single dose of those vaccines is only 33% effective against the more contagious delta variant of COVID-19, which has become the most prevalent strain of the virus in the United States and is likely to become more prevalent locally,” said Denise Foster, the county’s chief nursing officer.

“San Diegans who are overdue for their second shot should take action as soon as possible to lower their risk of getting or spreading the virus,” she said.

Everyone 12 years and older is eligible to get a COVID-19 vaccine at no cost. Visit for a full list of hours and locations of vaccine sites in the County.

Chris Jennewein

Chris Jennewein is Editor & Publisher of Times of San Diego.