A nurse from San Diego who received the Pfizer vaccine during the initial launch was diagnosed with COVID-19 infection on December 26, despite having been vaccinated more than a week earlier.
ABC 10 News report that the nurse, identified by Matthew W., works as an emergency room attendant at two separate hospitals in Southern California and only noted that after receiving the vaccine, her arm was sore, but had no other side effects.
Then, on Christmas Eve, after a change to a COVID-19 unit, Matthew became ill with symptoms that included chills, muscle pain and fatigue.
On December 26, he tested positive for COVID-19.
Although disappointing, this result is not unexpected among public health experts, officials say.
“It is nothing unexpected. If you work with the numbers, it is exactly what we would expect to happen if someone were exposed,” Christian Ramers, an infectious disease specialist at the Family Health Centers in San Diego, told reporters.
Ramers also notes that it is possible that Matthew was infected before receiving the vaccine, and the onset of symptoms occurred after he was vaccinated.
“We know from the clinical trials of the vaccine that it will take about 10 to 14 days for you to start developing vaccine protection,” he added.
At that time, Matthew also received only a single dose of the vaccine. The Pfizer vaccine is composed of two separate vaccines, which must be administered intravenously three weeks apart.
Documents published by the Centers for Disease Control and Prevention in the United States, it shows that a single dose of the Pfizer vaccine produces an average rate of effectiveness of 88.9% in preventing infections. The researchers note that the lack of data available for results with participants who received only a single dose of the vaccine “cannot support a conclusion about the effectiveness of a single dose of the vaccine”, since the majority of participants in clinical trials received both the doses.
Ramers says the rate of effectiveness after the first dose of the vaccine is likely to be around the 50 percent mark, and the second dose produces 95 percent stronger efficacy against the virus.
“You hear healthcare professionals being very optimistic about this being the beginning of the end, but it will be a slow process, weeks to months as we launch the vaccine,” added Ramers.