Health & Wellbeing

Not All COVID Jabs Work Equally Well For the Delta Strain

Natalia J.

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According to the latest estimates, over half of the new coronavirus infections in the United States are attributed to the Delta variant of the novel coronavirus. Similar estimates are observed across the globe. The public has been assured by COVID vaccine manufacturers that existing jabs protect vaccinated individuals from the new, increasingly transmissible variant of the virus.

But just how well do existing vaccines prevent illness and hospitalizations? A number of recent research articles estimated the effectiveness of three different COVID-19 vaccines against the Delta variant. Here’s what they found.

The Delta Variant Is Spreading More Rapidly Than Expected

Just a month ago, the CDC reported that the Delta Variant of COVID-19 accounted for only 6 percent of existing cases in the United States. More recent estimates suggest that the number has risen to 58 percent. Similar numbers are recorded in other parts of the world, with some regions - like the UK - reporting that as many as 99% of new COVID cases are triggered by the Delta strain.

Delta Strain and Vaccine Effectiveness virus

Before you get worried, let us reassure you - there is a silver lining. According to Dr. Leslie Bienen, a public-health researcher at Oregon Health, and Dr. Monica Gandhi, an infectious disease physician, and professor of medicine at UCSF, vaccines can protect the public from severe COVID-19. “When we look at current hospitalization data across the country, the most striking predictive pattern is that a high vaccination rate in a region accurately predicts a lower hospitalization rate,” the two medical experts wrote in an article for the Wall Street Journal.

While new COVID cases continue to rise, the number of hospitalizations is steadily dropping, especially in areas where most people were vaccinated. This confirms previous estimations suggesting that current vaccines work against the Delta strain. Studies from all across the globe confirm that existing vaccines work against the Delta variant, although not all vaccines are equally effective at protecting you from the new strain. Here’s a closer look at three common vaccines.

The Pfizer-BioNTech Vaccine

There are currently five different studies that measured the effectiveness of the Pfizer-BioNTech Vaccine for the Delta variant. All in all, the studies suggest that the Pfizer vaccine has an efficacy of 64-96% against the Delta variant, and those who do catch the new strain seem to have much milder symptoms. This is for patients who were completely vaccinated against the virus. Those who only got one dose of the vaccine are not getting nearly enough protection from the novel COVID strain.

Delta Strain and Vaccine Effectiveness Pfizer

By far the biggest study was conducted by Public Health England. It tested 14,019 participants from England and found that the Pfizer jab is 96% effective at preventing hospitalizations, 88% - at exhibiting any symptoms, and 80% - at catching the Delta variant.

A different article published in Nature stated that the Pfizer vaccine was more potent at protecting participants from the Delta strain than a prior COVID infection, so even recovered patients may soon need a booster shot to be protected from the Delta variant.

The research with the most conservative findings was carried out in Israel. The study suggests that the Pfizer vaccine is 64% effective at curbing infections and symptomatic COVID-19 caused by the Delta strain. It needs to be noted that the rollout of vaccinations in Israel began more than 6 months ago, which opens up the possibility that the effectiveness of the vaccine drops after half a year. This spurred discussions and studies over the need for a third booster shot against the Delta strain. However, currently, there is no such recommendation by the FDA or any other health authority.

The Moderna Vaccine

Delta Strain and Vaccine Effectiveness Moderna

Image Source: Governor Tom Wolf/ Wikimedia Commons

The second mRNA vaccine - the Moderna vaccine - also has a few studies backing its effectiveness against the Delta variant. Although few of these studies suggest specific numbers, the overall conclusion is that they either offer similar protection as the Pfizer jab or comparable protection compared to the original (alpha) variant of COVID-19.

One Canadian study even estimated that the Moderna vaccine is 72 percent effective against the Delta strain from a single dose, but they didn’t have enough fully vaccinated participants to measure the exact effectiveness of the Moderna vaccine after the second dose.

Like Pfizer, Moderna is currently exploring the possibility of a third booster dose. As Stéphane Bancel, CEO of Moderna, stated, “these new data are encouraging and reinforce our belief that the Moderna COVID-19 vaccine should remain protective against newly detected variants.”

The Johnson & Johnson Vaccine

Delta Strain and Vaccine Effectiveness Johnson & Johnson

Compared to the vaccines we mentioned previously, the data regarding the effectiveness of the Johnson & Johnson COVID-19 vaccine against the Delta strain is limited. This doesn’t mean that the vaccine is not effective, it’s just not very widely researched.

One clinical trial reported an 85% protection from a severe form of COVID. An even smaller study with only 20 participants also confirmed that the vaccine produced antibodies for the Delta strain 29 days post-vaccination. Johnson & Johnson’s data suggests that their vaccine offers lasting protection against the Delta variant, as stated in their recent press release.

Other Vaccines and Conclusions

The bottom line is, existing COVID-19 vaccines offer good but varying protection against the Delta strain of the virus. At present, the World Health Organization recognizes the Pfizer and AstraZeneca vaccinations as capable of preventing severe illness due to the Delta variant. Independent studies suggest that the Moderna and Johnson & Johnson vaccines have similar benefits. But little can be said about the prevention of mild COVID-19 cases caused by the Delta strain.

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