W.After being vaccinated against Covid-19, I felt a deep relief: no more worries about contracting the disease personally.
So when I noticed mild, Covid-19-like symptoms two months later – stuffy nose, chest congestion, and upset stomach – I thought they were due to seasonal allergies. I was shocked a few days later when a test for Covid-19, done in preparation for an unrelated medical procedure, came back positive.
Since I did not believe the result, I was retested. And again. Over a five day period, I had four PCR tests – two were positive, two were inconclusive – and a false negative rapid antigen test.
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I quickly quarantined and notified recent contacts. I soon received multiple calls from my city’s health board, whose representative told me she knew several other people who had also tested positive, even though they had been fully vaccinated.
My experience shows that testing for Covid-19 is not perfect. Rapid antigen tests detect proteins that are part of SARS-CoV-2, the virus that causes Covid-19. They have a fast turnaround time, but are not as accurate as the gold standard PCR test. In people with Covid-19 symptoms, rapid tests correctly detect the virus only 80% of the time. In people without symptoms it drops to 40%.
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PCR tests, on the other hand, tend to have much higher sensitivities, more than 95% across the board.
The way samples are collected can also affect the results of Covid-19 testing. I know this is happening because I’ve had a lot of Covid-19 tests in the last year. At some testing centers, the doctor placed the cotton swab at the very back of my nose, also called the nasopharyngeal space. Some say it feels like the cotton swab is entering the brain. In other testing centers, the doctor barely scraped the bottom edge of my nose; that’s called a nasal swab. They made me wonder if it collected a sample at all. I have since learned that nasal swabs cannot detect the virus in people with a low viral load.
While vaccination offers essentially 100% protection against Covid-19-related hospitalization and death, it does not completely prevent people from contracting the infection.
A recent study from the University of California, San Francisco, tracking more than 30,000 health professionals, showed a post-vaccination infection rate of about 1%, meaning infection is rare, but still a threat. The Minnesota Department of Health announced that it was investigating several of these “breakthrough” cases, as was the Oregon Health Authority. In mid-April, the Centers for Disease Control and Prevention reported 5,800 breakthrough infections among the millions of Americans who have been fully vaccinated so far.
Reports of 95% efficacy in vaccine clinical trials do not necessarily translate to effective efficacy of that magnitude, and may create a false sense of reassurance about asymptomatic or mild infections. The Pfizer studies tested volunteers for SARS-CoV-2 only if they developed symptoms after receiving the vaccine or placebo, disregarding those who may have been asymptomatically infected. Modern studies also primarily looked at the incidence of symptomatic diseases.
The lower efficacy rates in the J&J vaccine clinical trials may be more realistic, as they included asymptomatic participant PCR testing, had more diverse patient populations, and were performed later in the pandemic, when more viral variants were identified. These differences may explain the lower efficacy of this vaccine – 74% for prevention asymptomatic infections – compared to 80% for the Pfizer and Moderna vaccines, according to a recent study from Mayo Clinic.
Here’s what I think all of this means.
No vaccine is 100% effective in preventing Covid-19. However, the ones we have are very effective at preventing serious illness, death and reducing viral load in people unlucky enough to contract breakthrough infections after vaccination. The focus now must remain on vaccinating – and testing – as many people as possible as soon as possible so that we can end the pandemic as soon as possible. To do this, we need more streamlined access to vaccinations and testing.
Regardless of vaccination status or previous infection, anyone with signs or symptoms of Covid-19 should be tested, as well as anyone who has been in close contact (within 6 feet for 15 minutes or more) with someone with a confirmed Covid-19. According to the CDC, people who are fully vaccinated and have no symptoms after an exposure should not be tested.
In Massachusetts, where I live and work, the Stop the Spread initiative and organizations like Transformative Healthcare are making free Covid-19 testing more widely available.
At the federal level, Biden’s government has already issued multiple executive orders to address the virus and expand Covid-19 testing for children and disadvantaged populations, including a $ 650 million investment for elementary schools and homeless shelters.
Even with nearly 25% of the U.S. population fully vaccinated, I – and others like me – am proof that now is not the time to abandon our guards. Vaccines are needed, but not enough to deal with Covid-19. Get vaccinated, but don’t be careful about wearing a mask, basic hygiene and physical distance. It is not until we establish immunity to the herd that we can achieve our goal of eradicating this virus.
Stephen M. Tourjee is a child and adolescent psychiatrist; founder of Northshore Minds, a mental health practice north of Boston; associate director of the Transitional-Age-Youth Program at Massachusetts General Hospital; and a teacher of psychiatry at Harvard Medical School.