COVID-19 Vaccines Are Still Effective Amid Rising Number of Variants
- Data from vaccine clinical trials and real-world evidence show that even in the face of variants, the coronavirus vaccines can drastically cut the risk of severe disease.
- The immune system is complex enough that antibodies and T-cells may mount successful attacks on the virus, even if it mutates.
- Past vaccines for diseases like measles have led to durable protection that can last decades.
With so many news headlines focusing on the variants and their potential to prolong the pandemic, it’s no wonder that people have become increasingly concerned that the vaccines won’t work as well against mutations.
But infectious disease doctors say that even if antibody levels drop in the months following vaccination, the immune system is complex and robust. We’ll be well protected against variants, they say, with a lower risk for disease, hospitalization, and death.
The key question is, just how well do the vaccines work against the variants?
According to experts, well enough that vaccinated people don’t need to worry too much about the current known variants.
Data from vaccine clinical trials and real world evidence show that even in the face of variants, the coronavirus vaccines can prevent infection and drastically cut people’s chances of severe disease and hospitalization.
There’s plenty of evidence, both from vaccine clinical trials and the real world, which demonstrate the vaccines’ ability to protect us against the variants.
Recent research from Pfizer looked at 44,000 people around the world — including people in South Africa who were predominantly exposed to the B.1.351 variant — and found that the vaccine remained 100 percent effective against severe disease and death.
Real-world data also shows that the Pfizer vaccine held up against the B.1.1.7 variant, which was first detected in United Kingdom. Even in an area where B.1.1.7 was the dominant strain, the shot was 97 percent effective against symptomatic COVID-19, hospitalizations, and death.
Johnson & Johnson vaccine clinical trials were conducted in South Africa and Brazil — both of which were being pummeled by the B.1.351 variant and P.1 variant, respectively, when the trials were conducted.
Though the Johnson & Johnson vaccine was less effective overall against mild and moderate disease in South Africa and Brazil, the one-dose shot still provided strong protection against hospitalization and death.
The main takeaway is that the vaccines work well against the variants, especially when it comes to preventing severe disease and death.
Though some lab studies have shown that the initial antibody response appears to wane a few months after vaccination, infectious disease experts widely agree that measuring antibodies doesn’t paint the full picture of protection.
The immune system is complex, and antibodies alone won’t determine how protected you are against a pathogen, explains Dr. Joseph Craft, a professor of immunobiology and medicine at Yale School of Medicine.
The cell-mediated immune response , which includes B-cells that produce antibodies along with T-cells, also mount a robust response against pathogens, often lasting for years.
Our antibodies help prevent an infection from occurring by neutralizing a virus, but the T-cells can recognize parts of the virus on infected cells and clear out the infection before it becomes serious.
“T-cell response is much broader than the B-cell response to patients who’ve been vaccinated, and that’s not surprising because T-cells will recognize multiple parts of the virus,” explained Craft.
Detectible antibody responses typically drop with other viruses, according to Craft. But memory B-cells and T-cells usually persist, and when exposed to a pathogen in the future, can put up a good fight.
We don’t hear about T-cells as much because they’re more difficult and expensive to measure compared to antibodies, explains Dr. Monica Gandhi, an infectious disease specialist with the University of California, San Francisco.
“Antibodies are a dime a dozen. They’re very simple to measure, so that’s why we have antibody study after antibody study,” Gandhi said.
All of the vaccine clinical trials “showed us that our T-cells rise with vaccines, and even though you are hearing all these stories, know that the T-cells work against the variants,” Gandhi said.
According to Craft, once our bodies have been exposed to a virus, we’re typically protected against that virus for a long time.
Early evidence suggests our coronavirus-specific T-cell response will be durable, too.
A recent paper determined that the variants — including B.1.1.7, B.1.351, P.1, and CAL.20C — had no meaningful impact on the T-cell response.
The study found people had “strong T-cell responses to those variants equal to the T-cell responses you get from the ancestral strain,” Gandhi explained.
Scientists will need to continue studying T-cell immunity over time to understand just how protective and durable our cell-mediated response is.
“Memory is not perfect. It’s pretty darn good, and that’s one reason we are long-lived mammals,” Craft said.
There’s growing concern that the variants could evade our vaccines, but many infectious disease doctors say that there’s reason for optimism.
Even if antibody levels drop in the months following vaccination, the immune system is complex enough that vaccinated people will be well protected against variants and have a lower risk for disease, hospitalization, and death.