Some healthcare workers have reported falling ill with COVID-19 after getting their first vaccine dose -- but that's not a surprise, as protection can take as long as 2 weeks to kick in, researchers said.
A nurse from California made headlines last week after getting sick 6 days after he received his first shot. Since then, other healthcare workers have shared similar experiences on social media.
Trauma surgeon Qaali Hussein, MD, for example, developed COVID-19 12 days after her first COVID-19 injection.
"I'm 12 days post 1st dose of the vaccine so I do not have full protection yet," Hussein wrote on Twitter, stating that she should have at least some protection from severe illness. "I think we definitely need to ramp up vaccinations and would highly recommend getting vaccinated as soon as you are able to."
Emily Porter, MD, a physician in Austin (and sister of California Rep. Katie Porter [D]), also got sick with COVID-19 a few days after getting immunized. Josh Mugele, MD, an emergency physician in Georgia, reported mild symptoms 8 days after his first dose.
"The vaccine is still the best weapon we have, but we still need to mask up, wash our hands and isolate," Mugele wrote on Twitter.
Despite reports of illness onset after vaccination, experts say there is no cause for concern. The number of doses received, how long it takes to develop an immune response, and the time of viral exposure all play a role in whether or not people who have received the vaccine will still get sick.
Both the Pfizer/BioNTech and Moderna mRNA shots require two doses to provide maximum protection. Gregory Poland, MD, a spokesperson for the Infectious Diseases Society of America and an internal medicine physician at the Mayo Clinic who studies vaccines, said it can take up to 2 weeks after the first dose to develop a sufficient antibody response.
"When you get your first dose of vaccine, you will develop an immune response from that. But it takes time -- in the neighborhood of 7 to 14 days -- for that antibody response to develop, much less be at a level that's protective," he said.
Three to four weeks after the first injection, a second shot boosts the immune response, cementing antibody production into cell memory. "Giving a second dose is important to pushing that antibody level up as high as you can go to give the maximum amount of time before it wanes below a protective threshold," Poland added.
Peter Katona, MD, an infectious diseases physician at the University of California Los Angeles, agreed that the simple answer to why people are getting sick after vaccination is that not enough immunity has been built up yet.
Results from Pfizer/BioNTech's late-stage clinical trial suggest one dose of the vaccine might confer some level of immunity, with an efficacy rate around 52%. But the one-dose regimen has not received any sort of government approval, as vaccine efficacy jumps to 95% after the second dose.
Aside from the number of doses taken and the time it takes to develop immunity, Poland said distribution logistics for the vaccines might also impact efficacy.
Both have specific guidelines and need to be stored at extremely cold temperatures. "Once the vaccines exceed the time they can be at refrigerator or room temperature, they begin to rapidly degrade in quality," Poland stated.
Amid a slower-than-expected vaccine rollout, experts said it is critical for people who have been immunized to continue infection control methods.
"Even though you received the vaccine, you still have to do all the steps that we're doing right now," said Deepak Aggarwal, MD, chief of medical staff at the Northeast Georgia Medical Center in Gainesville, including hand-washing, mask-wearing, and physical distancing.
https://www.medpagetoday.com/infectiousdisease/covid19/90584
