The days of worrying about that tickle in your throat may not be entirely behind you after getting vaccinated against the coronavirus. Doctors in Boston, Massachusetts, say it's important to get tested when experiencing symptoms, even for inoculated individuals.
"Although the vaccines are highly effective, they are not 100% effective," said Dr. Daniel Kuritzkes, chief of the infectious diseases division at Brigham and Women’s Hospital. "People having symptoms of COVID-19 should definitely be tested even if they have been vaccinated."
According to medical experts, so-called breakthrough cases — cases where fully vaccinated individuals test positive for coronavirus — have so far been rare, but are possible.
"It is critical that we know if vaccinated people are breaking through the protection of the vaccine, which could mean that there is a viral variant capable of evading the immune response induced by the vaccine," said Dr. Eric Rosenberg, an infectious disease physician and director of the clinical microbiology laboratory at Massachusetts General Hospital.
A total of 10,262 breakthrough infections were reported in the U.S. as of April 30, at which time 101 million people had been vaccinated, according to the U.S. Centers for Disease Control and Prevention.
As of June 5, there have been 3,641 cases of COVID-19 among 3,500,011 fully vaccinated individuals in Massachusetts, according to the Department of Public Health. That's 558 more cases than the 3,083 fully vaccinated people who had tested positive for coronavirus in Massachusetts as of mid-May.
"While most people with 'breakthrough infection' tend to be less contagious, there is still a possibility of spreading the infection to others if one does not isolate," said Dr. Shira Doron, an infectious disease physician and hospital epidemiologist at Tufts Medical Center.
The virus is "constantly mutating," according to Doron, so multiple variants are to be expected.
In fact, the more contagious Delta COVID-19 variant, first identified in India, has been in Massachusetts for weeks now and is steadily rising. Experts say the Delta variant is more contagious and may be associated with a higher risk of hospitalization than the original "wild type" COVID-19 strain.
"It is only by testing individuals with COVID symptoms that we can sequence virus and determine if the vaccine breakthrough is caused by a variant," Rosenberg said.
In addition to figuring out whether the vaccines protect against any variant that develops, doctors emphasized the importance of getting tested even after getting vaccinated to prevent further spread.
"It is important for people who might experience a breakthrough infection to be aware that they have COVID-19, stay home from work and isolate until they are recovered, just as for people who have not been vaccinated," Kuritzkes said.
If vaccinated individuals become infected, they are likely to have a more mild version of the virus, according to Rosenberg. But they are still capable of infecting vulnerable people, including adults and children who haven't been vaccinated.
"These vulnerable people can not only get very sick from COVID but they also will serve as a 'reservoir,' keeping COVID in circulation in the community," Rosenberg said.
When to get tested
When should vaccinated individuals get tested? And how mild or severe would the symptoms need to be to warrant a test?
"Any symptoms consistent with COVID warrant testing," Rosenberg said. "Vaccinated individuals will most likely have more mild symptoms but any symptoms -- mild or severe -- deserve testing."
Doctors say people should get tested if they develop flu-like symptoms, including fever, sore throat, shortness of breath, loss of taste or smell, muscle aches and pains or a cough.
"The CDC guidance recommends testing with symptoms suggestive of COVID-19 either mild or severe. Therefore, we recommend that fully vaccinated individuals get tested as soon as possible," said Dr. Sabrina Assoumou, an infectious disease physician at Boston Medical Center.
Kuritzkes added that he would have an even lower threshold for testing if someone had recently been exposed, for the immunocompromised and for high-risk individuals.
Doron noted that fully vaccinated individuals should not, however, participate in screening programs targeting asymptomatic individuals.
"This is because all tests have a false positive rate, and given how rare breakthrough infection is, a positive test in a fully vaccinated individual is more likely than not a false positive," Doron said. "This concept uses the same public health principal as screening for cancer, in that we do not do screening mammograms on women in their 20s."
How long will public health experts continue to encourage vaccinated people to get tested?
"That’s hard to say. I expect testing will continue to be encouraged under the circumstances indicated above until we see cases disappear," Kuritzkes said. "The confusing issue will be that as we get back towards 'normal' and more people are gathering indoors without masks, we are likely to see a resurgence of standard, run-of-the-mill respiratory infections (i.e., the common cold)."
Doron said she believes that testing for symptomatic people will continue until COVID-19 becomes "extremely uncommon."
Rosenberg agreed that the recommendation will likely continue as long as COVID-19 is circulating in the community.
"It is easy to get tested, and it is the only way that we can assess the status of the pandemic in 'real time' and continuously monitor for viral variants and determine vaccine effectiveness," Rosenberg said.
"Although vaccination is our way 'out' of the pandemic, testing remains one of our most critical tools to monitor infection and disease activity in our area and to proactively react to any changes. Continued testing is also the only way to do contract tracing so we can understanding who may be spreading COVID and who may be at risk."