How vaccines stack up against the CDC’s 5 worrying variants
The CDC designated the delta variant of the coronavirus – first identified in India – as a ‘variant of concern’ on June 15, rekindling attention to the race between vaccines and variants of the coronavirus.
The new classification comes amid growing evidence that the variant spreads more easily than existing strains and causes more serious infections, the CDC said in a June 15 statement to Becker. People infected with the delta variant may be twice as likely to be hospitalized as those infected with the alpha variant first identified in the UK, according to a study released this week in Scotland. In May, the UK’s Scientific Advisory Group for Emergencies also said the delta variant could be up to 50% more transmissible than alpha, which is currently the dominant strain in the US, although research is still preliminary.
The delta variant now accounts for about 10% of COVID-19 cases in the United States and could become the dominant strain in the country by this fall, according to Scott Gottlieb, MD, a former FDA commissioner who now sits on the board of administration of Pfizer.
The good news? The vaccines offer strong protection against this variant, underscoring the importance of sustaining vaccination efforts to prevent the Delta from gaining a foothold in the United States, said Anthony Fauci, MD, director of the National Institute of Allergy and Disease. infectious diseases on June 8.
The vaccines also offer different levels of protection against the other four CDC variants of concern.
In June 2020, the FDA mentionned any COVID-19 vaccine candidate would need to reduce the risk of infection or serious illness by at least 50% to be considered for emergency use authorization. At the time, infectious disease experts including Dr Fauci hoped COVID-19 vaccines would surpass the 50% efficiency mark.
“I would like it to be 75 percent or more,” Dr. Fauci mentionned at an event in August 2020, before vaccines were approved for use in the United States
The three COVID-19 vaccines approved in the United States overwhelmed the 50 percent guideline: Pfizer’s vaccine was shown to be 95 percent effective in clinical trials, Moderna’s was 94 percent effective, and Johnson & Johnson’s vaccine was 66 percent effective, according to the CDC.
Although these clinical trials were conducted before the emergence of these variants, the emerging data is encouraging, as the vaccines still exceed the FDA’s initial expectations of 50% protection against the new strains.
Below is a summary of the existing research on the vaccine’s effectiveness for each of the CDC’s variants of concern. The variants are listed in alphabetical order.
Alpha, first detected in UK: In April, it became the dominant strain in the United States. It is believed to be about 50 percent more transmissible than the original strain, a growing body of research has indicated that the alpha variant has minimal effect on the neutralization generated by current vaccines or during previous infections.
A real world study from Qatar, where the variant made up about 45% of cases in mid-March, showed Pfizer’s vaccine to be nearly 90% effective against the strain two weeks after the second dose.
Lab tests have also shown that Moderna’s vaccine protects against the variant: a January study posted on the Preprint server bioRxiv found no significant difference in the stroke’s ability to neutralize against alpha compared to earlier strains.
Beta, first detected in South Africa: This strain is about 50 percent more transmissible than previous versions, according to the CDC. Although considered the “nastiest of all variants,” according to Laith Abu-Raddad, PhD, infectious disease epidemiologist at Weill Cornell Medicine-Qatar, studies have offered promising results on the ability of vaccines to prevent infection. through beta.
In the same real-world study of Qatar referenced above, published May 5 in The New England Journal of Medicine, the researchers found that the Pfizer injection was 72% to 75% effective in preventing infection caused by the variant at least two weeks after the second dose. At the time, beta was responsible for around half of all COVID-19 cases in Qatar.
“It’s not the 95 percent we were hoping for, but the 75 percent is really amazing,” said Dr. Raddad, who is also one of the study’s authors.
When it came to preventing serious illness, Pfizer’s vaccine offered almost total beta protection.
In the laboratory, researchers observed a six-fold reduction in neutralizing titers – a measure used to indicate the concentration of antibodies in the blood – produced by the Moderna shot. Despite the reduction, neutralizing titers against the strain remained above levels that should be protective, according to the study.
Gamma, first detected in Brazil: Early research suggests vaccines offer reduced protection against infections caused by this strain, CDC says. While little actual data has been published on the effectiveness of vaccines against this strain, Moderna mentionned a reminder that it develops “should be protective” against the strain on the basis of the first data from clinical trials published May 6.
A small 20-person clinical trial from Johnson & Johnson found that its vaccine stimulated 3.3 times fewer neutralizing antibodies against the gamma variant compared to the strain originally circulating. However, the single-injection vaccine prevented severe COVID-19 in 88% of participants in Brazil and 82% in South Africa, where beta and gamma variants are prevalent.
Delta, first identified in India: Real world data shows that vaccines are very effective against this variant. In one recent analysis of 19,543 people in Scotland, Pfizer’s vaccine was 79% effective in preventing infection with the delta variant. Research from Public Health England suggests that protection could be even higher. The study, published on May 22, found that Pfizer’s vaccine was 88% effective against the variant two weeks after the second dose.
Finally, a separate study out of 14,019 people in England found that two doses of Pfizer’s vaccine were 96% effective in preventing hospitalizations due to the delta variant.
Epsilon, first detected in CaliforniaVaccines may be less effective against this variant, which is about 20 percent more transmissible than previously circulating strains, according to the CDC. The agency cited the preliminary lab research published on March 9 in the medical preprint server medRXiv, which found a double decrease in neutralizing titers in vaccine recipients against this strain. The study was not peer reviewed.
New research proves to be more optimistic. A research letter published on April 7 in The New England Journal of Medicine found only a slightly lower value of neutralization titers against the variant after analyzing virus samples from 49 people who received the Moderna or Novavax vaccine. Based on their findings, the researchers concluded that the vaccines would “likely remain effective” against the variant. Outside of this laboratory research, there is little clinical data on the vaccine’s protection against the epsilon variant in the real world.