A San Diego nurse who received the Pfizer vaccine during initial deployment was diagnosed with a COVID-19 infection on Dec. 26, despite being vaccinated more than a week earlier.
ABC 10 News reported that the nurse, identified as Matthew W., works as an emergency in two separate hospitals in Southern California, only noticing that his arm was sore but had no other side effects.
Then, on Christmas Eve, after a shift in a COVID-19 unit, Matthew became ill, with symptoms such as chills, muscle aches and fatigue.
On December 26, he tested positive for COVID-19.
Although disappointing, this result is not unexpected among public health experts.
“This is not unexpected at all. If you work through the numbers, this is exactly what we would expect to happen if someone were exposed,” Christian Ramers, an infectious disease specialist at Family Health Centers of San Diego, told reporters .
Ramers also notes that it is possible that Matthew was infected before receiving the vaccination, and that the symptom developed after he was vaccinated.
“We know from clinical trials of the vaccine that it will take about 10 to 14 days before you start developing protection against the vaccine,” he added.
At that point, Matthew also received only a single dose of the vaccine. The Pfizer vaccine consists of two separate vaccines that must be administered intravenously three weeks apart.
Documents issued by the U.S. Centers for Disease Control & Prevention, shows that a single dose of Pfizer vaccine has an average efficacy rate of 88.9 percent to prevent an infection. Researchers note that a lack of available data for the outcomes with participants who received only a single dose of the vaccine ‘could not support a conclusion about the efficacy of a single dose of the vaccine’, as most participants to clinical trials received both doses.
Ramers says that the effectiveness rate after the first dose of the vaccine is probably around 50 percent, and that the second dose provides a stronger effectiveness of 95 percent against the virus.
“You hear health practitioners are very optimistic that this is the beginning of the end, but it’s going to be a slow roll, weeks to months as we roll out the vaccine,” Ramers added.