A nurse in California tested positive for COVID-19 more than a week after receiving Pfizer Inc's vaccine, an ABC News affiliate reported on Tuesday, but a medical expert said the body needs more time to build up protection.
Matthew W., 45, 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.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
Christian Ramers, an infectious disease specialist with Family Health Centers of San Diego, told the ABC News affiliate that this scenario was not unexpected.
"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.
"That first dose we think gives you somewhere around 50 percent, and you need that second dose to get up to 95 percent," Ramers added.