Explained: Why California Nurse Tested COVID Positive Week After Receiving Pfizer Vaccine
A 45-year-old nurse in California tested positive for COVID-19 more than a week after receiving Pfizer Inc's coronavirus vaccine, an ABC News affiliate reported on Tuesday.
Matthew W, a nurse at two different local hospitals, said in a Facebook post on December 18 that he had received the Pfizer vaccine, telling the ABC News affiliate that his arm was sore for a day but that he had suffered no other side-effects.
Six days later on Christmas Eve, he became sick after working a shift in the COVID-19 unit, the report added. He got the chills and later came down with muscle aches and fatigue.
He went to a drive-up hospital testing site and tested positive for COVID-19 the day after Christmas, the report said.
But, how is it possible?
Christian Ramers, an infectious disease specialist with Family Health Centers of San Diego, told the ABC News affiliate that this scenario was not unexpected.
"It's not unexpected at all. If you work through the numbers, this is exactly what we¡¯d expect to happen if someone was exposed," said Christian Ramers.
He points out, it is possible Matthew was infected before receiving the vaccine, as the incubation period may be as much as two weeks. Dr. Ramers says if Matthew did contract it after the vaccine, it¡¯s still in line with what we know.??
10-14 days to develop protection
"We know from the vaccine clinical trials that it's going to take about 10 to 14 days for you to start to develop protection from the vaccine," Ramers said.
Ramers says he knows of several other local cases where health care workers became infected around the time they received the vaccine. He says all the cases illustrate the fact that results aren¡¯t immediate. Even after you start receiving some protection, it won't be full protection.??
"That first dose we think gives you somewhere around 50%, and you need that second dose to get up to 95%," Ramers added.
Basically, one needs to take two shots at least three weeks apart in order to be immune to the virus, for the time being.?
Meanwhile,?Matthew says he¡¯s feeling better since his symptoms peaked on Christmas Day, but still feels fatigued.?
