New data showing that two COVID-19 vaccines are far less effective in South Africa than in other places where they have been tested has heightened fears that the coronavirus is quickly finding ways to escape the world’s most powerful tools to contain it.
The American company Novavax reported this week that while its vaccine has been nearly 90% effective in clinical trials conducted in Britain, the number has dropped to 49% in South Africa – and that almost all infections the company has analyzed in South Africa involved the B.1.351 variant that emerged there at the end of last year and has spread to the United States and at least 30 other countries.
Johnson & Johnson announced on Friday that its new injection was 72% effective in preventing moderate or severe illness in the United States, compared with 66% in Latin America and 57% in South Africa.
Laboratory tests have suggested that vaccines authorized in the United States – one from Pfizer and BioNTech, the other from Moderna and the National Institutes of Health – trigger a minor immune response to the South African variant.
There is now evidence from testing in people that some variants are less vulnerable to certain vaccines.
“From an evolutionary biology perspective, this is fully expected and anticipated,” said Dr. Michael Mina, a Harvard epidemiologist. “But it is never good to be validated on something so scary.”
The researchers once believed that it would take several months, or even years, for the virus to develop resistance to vaccines. They said the rapid evolution is largely a result of the uncontrolled spread of the virus.
More than 100 million people have been infected worldwide and each of these infections is an opportunity for the virus to mutate at random.
A mutation that gives the virus an advantage – the ability to resist the body’s natural defenses, for example – can become the basis for a stronger variant.
One of the first signs that this process was underway was the significant number of people who contracted the coronavirus a second time. It appeared that the training their immune systems received during the first infection was failing to protect them from new versions of the virus.
Scientists at Moderna and Pfizer-BioNTech fear the same could happen with the immunity induced by their vaccines. In laboratories, they took several versions of the virus and exposed them to blood samples from a small number of people who had been vaccinated.
The neutralizing antibodies produced in response to the Moderna vaccine were equally effective against the original coronavirus and the B.1.1.7 strain that emerged in the UK, but were much less effective against the South African strain. The Pfizer vaccine was only slightly less effective against the South Africa variant compared to the others.
Experts warned that laboratory tests are an imperfect model for understanding the immune response in people.
Other parts of the immune system, such as T cells, can play a role in fighting a variant, even when neutralizing antibodies are insufficient, said Marc Lipsitch, a Harvard epidemiologist.
That is why the Novavax study – the first to test the interactions between variants and vaccines in the real world – was so worrying.
“If people who have been vaccinated become infected with the variant – that’s the real proof in the pudding,” said Otto Yang, an infectious disease researcher at UCLA.
Novavax warned that his study in South Africa, which included about 4,400 patients, was too small to provide an accurate measure of the vaccine’s effectiveness.
Johnson & Johnson’s results provided further evidence that the problem was serious.
Experts said the vaccine’s weaker performance in South Africa – where it was tested on about 6,500 people – was almost certainly a result of the predominance of the widely circulating variant there. The researchers believe it is more contagious than other variants and has become more common in South Africa and elsewhere since the test began in September.
The researchers said the variants are also responsible for the below-average display of the Johnson & Johnson vaccine in Latin America – where it was tested on more than 17,000 people in Argentina, Brazil, Chile, Colombia, Mexico and Peru.
The mutations of greatest concern are the peak protein on the surface of the virus, because the current crop of vaccines trains the immune system to recognize this protein. Mutations increase the likelihood that the virus will go undetected.
Mina, the Harvard epidemiologist, compared the process to looking for a criminal, memorizing only the appearance of his nose and mouth. At first, this may be sufficient. But if the criminal does a nose job, investigators will wish they had learned about their eyes, ears and hair as well.
Mina said that a more diverse arsenal of vaccines, using a variety of approaches, is needed.
In the meantime, Moderna announced efforts to develop a booster injection to add to its current two-dose regimen in order to move the South African variant away. The company also plans to test whether a third dose of the original formula could help with other strains.
BioNTech, the company that worked with Pfizer on its injection, is also considering developing a suitable vaccine.
The United States reported its first known cases of the South African variant on Thursday, in two people in South Carolina. The United Kingdom strain, which is also considered more contagious, is also circulating here.
In a briefing for reporters on Friday, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said confirmation that more communicable strains are now in the US is a “warning” that underscores the need to vaccinate Americans quickly.
“Vaccinating as many people as we can, as quickly as possible” is the key to decreasing the virus’ ability to mutate, he said. “Viruses cannot mutate if they cannot replicate.”
The United States is vaccinating an average of 1.2 million people a day, said Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention.
Experts say this is very slow, because there is no way of knowing what kind of advanced variants will exist when the vaccination campaign reaches critical mass.
They emphasize that vaccination must be accompanied by defensive tactics, such as masking and social detachment, until the number of cases is negligible.
“If you think you’re just going to get vaccinated to get away with it, it’s going to be like hitting a mole,” said Susan Butler-Wu, director of clinical microbiology at LA County-USC Medical Center.
An effective vaccination campaign should eventually spread across the world. If an impressive strain emerged next year, for example, in Brazil, even a fully vaccinated USA could be in danger.
“You can vaccinate hell outside of America,” said Mina, but “until everyone is protected, we’re all still at risk.”
Fauci called for strengthening the government’s ability to detect new viral mutations. Genetic sequencing efforts have been fragmented, with academics and other groups volunteering their findings. The US sequences only 1% of the millions of positive samples collected during routine coronavirus testing.
“We are aiming a flashlight in the dark, hoping to find dangerous variants,” said Anne Rimoin, a UCLA epidemiologist. “What we really need to do is turn on the lights.”