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New data showing that two COVID-19 vaccines are much less effective in South Africa than in other places where they have been tested have heightened fears that the coronavirus will quickly find ways to evade the world’s most powerful tools to contain it.
US company Novavax reported this week that while its vaccine was nearly 90% effective in clinical trials in Britain, the figure has dropped to 49% in South Africa – and that nearly all infections analyzed by the company in South Africa were the B.1.351 variant that appeared there late last year and has spread to the United States and at least 30 other countries.
Johnson & Johnson announced on Friday that its new vaccine was 72% effective in preventing moderate to severe disease in the United States, up from 66% in Latin America and 57% in South Africa.
Laboratory tests had previously suggested that the two vaccines licensed in the United States – manufactured by Pfizer-BioNTech and Moderna – trigger a weaker immune response to the South African variant.
Now, tests done on people show that certain variants are less vulnerable to certain vaccines.
“From an evolutionary biology perspective, this is totally expected and anticipated,” said Dr. Michael Mina, a Harvard epidemiologist. “But it never feels good to be validated on something so scary.”
Researchers once believed that it would take several more months, if not years, for the virus to develop resistance to vaccines. They said the rapid development was largely the result of the virus’ uncontrolled spread. 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 warmer variant.
One of the first signs that this process was underway was the large number of people who contracted the coronavirus a second time. It turned out that the training their immune system received during the first infection did not protect them from new versions of the virus.
Scientists at Moderna and Pfizer-BioNTech feared the same could happen with the immunity induced by their vaccines. In the labs, they took several versions of the virus and exposed them to blood samples from a small number of vaccinated people.
Neutralizing antibodies produced in response to Moderna’s vaccine were equally effective against the original coronavirus and the B.1.1.7 strain which emerged in the UK but were much less effective against the South African strain. Pfizer’s vaccine was only slightly less effective against the South African variant than the others.
Experts had warned that lab tests were an imperfect model for understanding the immune response in humans.
Other parts of the immune system, such as T cells, could play a role in fighting a variant, even when neutralizing antibodies are insufficient, said Marc Lipsitch, a Harvard epidemiologist.
That’s why the Novavax trial – the first to test interactions between variants and vaccines in the real world – was so concerning.
“That people who have been vaccinated get infected with the variant – that’s the real proof in the pudding,” said Dr. Otto Yang, infectious disease researcher at UCLA.
Novavax warned that its study in South Africa, which included around 4,400 patients, was too small to offer 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 poorer performance in South Africa – where it has been tested on about 6,500 people – was almost certainly the result of the predominance of the variant circulating widely there. Researchers believe it is more contagious than the other variants and has become more common in South Africa and elsewhere since the trial began in September.
The researchers said variants were also likely to be responsible for the poor performance of the Johnson & Johnson vaccine in Latin America – where it has been tested on more than 17,000 people in Argentina, Brazil, Chile, Colombia, Mexico and Peru.
The mutations of most concern are in the spike protein on the surface of the virus, as the current harvest of vaccines trains the immune system to recognize this protein. Mutations there increase the likelihood that the virus will pass undetected.
Mina likened the process to finding a criminal by memorizing only the appearance of his nose and mouth. At first, this may be enough. But if the criminal gets a nose job, you’ll find yourself wishing you had heard of his eyes, ears, and hair texture as well.
Mina said we need a more diverse vaccine arsenal, using a variety of approaches, to solve the problem.
In the meantime, Moderna has announced efforts to develop a booster to add to its current two-dose regimen in order to fend off the South African variant. The company also plans to test whether a third shot of the original formula might help with other strains.
BioNTech, the company that worked with Pfizer on its injection, is also considering developing a tuned vaccine.
The United States on Thursday reported its first known cases of the South African variant in two people in South Carolina. The British strain, which is also considered to be 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 the confirmation that more transmissible strains are now in the United States is a “wake-up call” that stresses the need to rapidly vaccinate Americans.
“Vaccinating as many people as possible, as quickly as possible” is the key to slowing the ability of the virus to mutate, he said. “Viruses cannot mutate if they cannot replicate themselves.”
The United States immunizes an average of 1.2 million people per day, according to Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention.
Experts say this is far too slow, as it’s unclear what kind of advanced variants will exist by the time the vaccination campaign reaches critical mass.
They stress that vaccination must be accompanied by defensive tactics like masking and social distancing until the number of cases is negligible.
“If you think you’re just going to vaccinate to get out of this, it’ll be like a mole hit,” said Susan Butler-Wu, director of clinical microbiology at LAC + USC Medical Center.
An effective vaccination campaign must ultimately spread across the world. If an impressive strain were to emerge next year, say in Brazil, even a fully vaccinated America could be in danger.
“You can get the hell out of America vaccinated,” Mina said, 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, relying on academics and other groups to voluntarily upload their results and disseminate them. In total, the United States is only sequencing 1% of the millions of positive samples collected during routine coronavirus testing.
“We shine a flashlight in the dark, hoping to spot dangerous variants,” said Anne Rimoin, epidemiologist at UCLA. “What we really need to do is turn on the lights.”
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