Breakthrough cases are post-immunization cases that are very rare and yet expected to happen. Experts are not yet sure when the first cases exactly appeared, but a slow trickle of post-vaccination infections has already started in the United States by January.
These breakthrough cases arose in the West, making headlines in Oregon, and some cases were also recorded in the Midwest and South. Meanwhile, the latest breakthrough cases were documented in Florida, Texas, and Hawaii just two weeks after people received their final COVID-19 shot.
However, experts said that the growing number of breakthrough cases is no cause for concern.
SEVERN, MARYLAND - MARCH 23: Maryland residents receive the Moderna COVID-19 vaccine through the Anne Arundel County Department of Health at a community COVID-19 vaccination clinic at the Metropolitan United Methodist Church on March 23, 2021, in Severn, Maryland. Nearly 2.4 million vaccines have been administered in the state of Maryland to date, representing just over 20 percent of the state’s population. (Photo by Win McNamee/Getty Images)
Vaccinated People Are Not Invincible
Breakthrough cases are a reminder that vaccinated people are not invincible, the New York Times reported. They too could get infected even after the COVID-19 vaccination. Though these cases are rare, they are also expected as the vaccines available today only offer around 94%-95% efficacy, proof that no inoculation is perfect.
Since mid-December, approximately 40 million Americans have already received the jabs for full immunization but a small percentage of them have gone on to test positive for the virus.
Experts said that this reminds people that wearing face masks and practicing other health protocols are still essential while coronavirus is still circulating.
"We felt really strongly that this data should not lead people to say, 'Let's all get vaccinated, and then we can all stop wearing masks,'" said UC San Diego Health infectious disease specialist Dr. Francesca J. Torriani. "These measures have to continue until a larger segment of the population is vaccinated."
Torriani, who led a study in California said that only some of the health workers in the state showed symptoms, which tend to be mild. This echoes the result from vaccine trials that indicate breakthrough cases were mild and do not require hospitalizations, while some exhibited no symptoms at all and were only discovered because of testing as part of their medical care.
Researchers said that this displays the protective side of the vaccine. It prevents the person from getting sick, even if it does not fully block the virus from infecting people.
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Vaccinated People's Exposure to the Virus Also Matters
The vaccines circulating in the United States right now are all designed around the original variant of coronavirus that causes COVID-19, which now seems to be less effective against the new versions of the virus. But that does not mean that these vaccines have become obsolete.
On the other hand, more breakthrough cases are recorded the more variants of the virus circulating the world, Yale vaccine expert Saad Omer told The Atlantic.
That means exposure to any version of the disease, even among vaccinated people, makes a difference. The more they spend time with unvaccinated people in places where cases are high, it raises their chances of getting sick.
Also, a large amount of virus could overwhelm the immune defenses if it does infect people. Immunity and the degree of defense activated by an infection or vaccine could differ from person to person. Some might only produce fewer or less potent antibodies and T-cells that can fight the coronavirus.
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