WWhen I was vaccinated against Covid-19, I felt a deep sense of relief: there are no more worries about getting caught.
So when I noticed mild symptoms, like Covid-19, two months later – stuffy nose, chest congestion and upset stomach – I thought it was 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.
Without believing the result, I was tested again. And again. Over a five-day period, we had four PCR tests – two were positive, two were inconclusive – and one false antigen-negative test.
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I quickly started quarantining and announcing recent contacts. I soon started receiving several calls from my city’s Health Council, whose representative told me that he knew of a few other people who also tested positive, even though they had been completely 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 response 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. For those without symptoms, it drops to 40%.
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In contrast, PCR tests tend to have much higher sensitivities, over 95%.
The way samples are collected may also affect the results of Covid-19 testing. I know this is because I have had many Covid-19 tests in the last year. At some test centers, the clinician inserted the swab into the back of my nose, known as the nasopharyngeal space. Some say the tampon seems to be pointing to the brain. In other test centers, the clinician barely scratched the underside of my nose; this is called a nasal swab. These made me wonder if he collected any samples. We have since learned that nasal swabs can lose the detection of the virus in those with low viral loads.
While vaccination essentially provides 100% protection against Covid-19-related hospitalization and death, it does not completely prevent people from catching the infection in the first place.
A recent study by the University of California, San Francisco, which looked at more than 30,000 health care workers, showed an infection rate after vaccination of about 1%, which means the infection is rare but still a threat. The Minnesota Department of Health said it is investigating several of these “discovery” cases, as is the Oregon Health Authority. In mid-April, the Centers for Disease Control and Prevention reported 5,800 infections discovered to date among millions of Americans who were completely vaccinated.
Reports of 95% efficacy rates in clinical trials with vaccines do not necessarily translate into actual efficacy of that magnitude and may create a false sense of reassurance when it comes to asymptomatic or mild infections. Pfizer studies tested volunteers for SARS-CoV-2 only if they developed symptoms after vaccine or placebo, leaving out those who could have been asymptomatically infected. Modern studies have also looked primarily at the prevention of symptomatic disease.
Lower efficacy rates in J&J vaccine clinical trials may be more realistic, as they included asymptomatic PCR testing of participants, had more patient populations, and were performed later in the pandemic, when several viral variants were identified. These differences may explain the lower efficacy rate of this vaccine – 74% for prevention asymptomatic infections – compared to 80% for Pfizer and Moderna vaccines, according to a recent study by Mayo Clinic.
This is what I think all this means.
No vaccine is 100% effective in preventing Covid-19. The ones we have, however, are very effective in preventing severe illness, death and reducing the viral load in people who are unhappy enough to get infections discovered after vaccination. The focus must now be on vaccinating and testing as many people as possible so that we can end the pandemic as soon as possible. To do this, we need more effective access to vaccinations and tests.
Regardless of the 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 (6 feet for 15 minutes or more) with someone with Covid- 19 confirmed. According to the CDC, people who have been completely vaccinated and have no symptoms after exposure should not be tested.
In Massachusetts, where I live and work, the Stop the Spread initiative and organizations such as Transformative Healthcare provide free Covid-19 testing.
At the federal level, the Biden administration has already issued several executive orders to fight the virus and extend Covid-19 testing to children and underserved populations, including a $ 650 million investment in K-8 schools and homeless shelters.
Even with almost 25% of the US population fully vaccinated, I – and others like me – are proof that now is not the time to let our guards down. Vaccines are needed, but not enough for the Covid-19 approach. Get vaccinated, but do not pay attention to the wind in terms of wearing a mask, basic hygiene and physical distance. We will not be able to achieve our goal of eradicating this virus until we establish immunity from the herd.
Stephen M. Tourjee is a psychiatrist for children and adolescents; the founder of Northshore Minds, a mental health practice north of Boston; associate director of the Transitional-Age-Youth Program for Massachusetts General Hospital; and psychiatry instructor at Harvard Medical School.