Researchers have started to answer some of the most vital questions when it comes to whether the current vaccines can smother the pandemic — providing 80 or 90% of the population gets the shot.
The published clinical trials on the Johnson and Johnson, Pfizer and Moderna vaccines focused on documenting whether the shots can prevent people from developing symptoms and getting seriously ill. The three approved vaccines proved 85 to 95% effective in preventing symptoms, with minimal side effects.
However, the initial clinical trials did not address other key questions. For a frequently updated summary of research go to the journal Nature at https://www.nature.com/articles/d41586-020-00502-w). So here are the highlights of a slew of new vaccine studies from around the world, reported in science journals.
• The leading US vaccines not only prevent disease and death, they dramatically reduce the odds a vaccinated person will pass the virus along at all.
• The vaccines also prevent the spread of many of the new variants, including those that spread faster and cause more serious disease.
• The vaccines may help ease the effects of “long COVID,” a cluster of symptoms that can linger for months after an initial infection.
• Even in the rare cases in which a vaccinated person does get infected – the shots appear to reduce the odds of developing serious side effects.
• If someone who has recovered from an infection gets a shot, they’re less likely to get reinfected — even by a different strain.
The studies mostly have underscored the value of the currently approved vaccines in finally controlling the pandemic, providing enough people get the shot. Much of the research remains preliminary and many of the published studies have not yet been peer reviewed, but so far the answers to most of the most important questions have been reassuring.
However, the vaccines won’t fully contain the virus until most people get their shots. And that’s a problem, since 20 or 30% of Americans say they don’t plan to get vaccinated. Already, places like Gila County have stopped offering vaccination clinics after working through the bulk of the older residents, high risk groups and essential workers. Even in some of those crucial groups — like teachers — only 75% opted to get the shot. Even in places like Gila County, where less than half-way to a level of vaccination that would really contain the pandemic.
Unless more people get shots, we won’t reach the relative safety of “herd immunity,” with so many people protected against infection that when new cases do crop up they can’t spread readily. That’s why vaccines helped the US eliminate diseases like smallpox and polio — although polio remains a danger in some countries with dysfunctional public health systems and low rates of vaccination. The same thing will likely happen with COVID for the foreseeable future, since many Third World nations have not even begun to vaccinate a large share of the population.
So health officials say it’s essential that people in the US continue to wear masks in public, socially distance and avoid crowds until everyone gets vaccinated. The federal Centers for Disease Control has issued guidelines that it is now safe to gather in small groups without masks so long as everyone in the group is vaccinated.
So here are some of the recent, encouraging studies filling in some of the key information about the impact of the approved vaccines.
• The Pfizer vaccine has proven 94% effective in preventing people who have gotten the shot from spreading the virus to anyone else, including asymptomatic infections. The study was based on repeated testing of vaccinated people in Israel.
• Several studies also conducted in Israel, which has vaccinated most of its population, found that the vaccine reduced viral loads by up to 20-fold within several weeks of vaccination. Other studies have linked viral concentrations in the nasal cavity with both the rate of infection and serious illness.
• Moderna compared 14,000 people who got the shot to 14,000 in a placebo group. The study found that 14 people in the group that got the shot developed infections without symptoms, compared to 38 in the placebo group. The researchers concluded the Moderna shot – which is the one used locally – reduced overall transmission by 91%.
• Studies of the Pfizer vaccine in monkeys found that the shot reduced any type of transmission of the virus by 85%, both with and without symptoms.
• A study of 39,000 Americans who got either the Pfizer or Moderna vaccine found even after one dose people were 72 % less likely to test positive for an asymptomatic infection within 10 days.
• Johnson and Johnson tested 3,000 people 71 days after they received the shot for signs of an asymptomatic infection. Only two people in the vaccinated group tested positive compared to 16 people in the placebo group. The analysis suggested the shot was 74% effective in prevent asymptomatic spread.
• New more infectious strains aren’t as vulnerable to antibodies produced by both vaccinations and a previous infection – but remain vulnerable to immune system T -cells stimulated by the vaccines as well as most infections.
• Some two-thirds of the residents of the Brazilian city of Manaus have been infected by the original, dominant COVID-19 strain, but now the city’s suffered a second wave of infections – and re-infections – from the new, P-1 strain. The new strain is roughly twice as infectious and apparently more likely to cause serious disease. The research underscores the importance of widespread vaccinations to prevent waves of infections and re-infections by new strains.
• The two-shot Pfizer vaccine worked just as well in Israel’s mass-vaccination effort as it did in clinical trials – which means it proved 94% effective in preventing any symptoms and 92% effective in preventing severe disease. Moreover, the highly infectious B.1.1.7 variant was circulating in Israel at the time, suggesting the shot works just as well against that variant.
• People remain sick longer when infected with some of the new variants, which may explain why the strains transmit more readily and perhaps cause more serious disease. The findings again underscore the need to vaccinate as many people as quickly as possible, to cope with the new strains.
• The Moderna and Pfizer vaccines increased by 1,000-fold the neutralizing antibodies against both the original COVID strain and two of the most dangerous and widespread variants. The study involved blood samples from from both China and South Africa.