Following the epidemic news too closely could be an emotional roller coaster, with horrific public health warnings promising new studies soon. The latest growing innovation: a new CDC study showing vaccines severely cut all Kovid-19 infections – not just symptoms. That news rests on a worst-case scenario: vaccines can protect hospitalized vaccines, but allow millions of silent infections to spread.
New data were collected from 4,000 health care workers, first responders, delivery workers and teachers who were vaccinated with the Pfizer or modern vaccine between December 2020 and March 2021. The study authors concluded that vaccines cause a 90% reduction in all infections. If people are not infected, they will not be able to spread the virus to others.
The next drop on the roller coaster may come from new virus variants, some of which have shown the ability to bypass the antibodies generated by the original strain. But experts like Paul Affit of Children’s Hospital in Philadelphia are even more optimistic. Vaccines show some efficacy against all currently known variants and a good efficacy against one – the B.1.1.7 strain identified in the UK last year.
Before the new study came out, Affit saw ample other evidence that transmission from vaccines had decreased, saying he liked the idea of issuing vaccine passports for travel, restaurants or other venues. Data from Israel, where most of the population has already been vaccinated, shows rapidly falling deaths and hospitalizations. “Nothing is foolproof,” he says, but people get along very well with others compared to others who have been vaccinated.
New study results should also reduce fears that the surprising clinical trial results of vaccines may not stand up in the real world. One concern is the small sample size. While thousands of people are enrolled in those tests, infections are so common that only a small number in the vaccinated arm or placebo group are infected.
In this new study, there were 161 infections in the control group of 994 unwanted individuals. In contrast, of the 2,479 people who were vaccinated, only eight became infected between their first and second doses, which were given over a period of three or four weeks. Only three people became infected after being fully vaccinated (two weeks after receiving the second shot).
Afit said it is very promising that vaccines not only boost antibodies, but also stimulate cellular immunity. That is, they stimulate the production of specific virus-fighting cells called T-cells, which act against a wider range of variants than antibodies. T-cells last longer than antibodies and give vaccines the energy to “remember” and fight off pathogens weeks or months later.
He was also excited about the Johnson & Johnson vaccine, although it was used by only five people in the CDC study. That vaccine stimulates cellular immunity just one shot, while the Pfizer and Modernna vaccines only stimulate T-cells after two shots. (For that reason, he does not advise skipping a second shot of two shots of vaccines to protect supplies.)
Monica Gandhi, an infectious disease doctor at UCSF, said she hopes the shots will effectively end the epidemic because T-cells can fight off different variants. “I understand that it is very good that vaccines are coming out of us,” she said. “But they do.”
One thing we have learned is that it is very difficult to control the course of this epidemic – how difficult it is to predict human behavior and the rapid evolution of the virus. Even vaccine optimists like Gandhi and Affit cannot see the eradication of the virus. They see the virus as less of a threat to life and health than the seasonal flu, and then it’s hard to get back to normal life – restaurants, international travel and, yes, roller coasters.