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Coronavirus

Does the Delta COVID-19 variant threaten vaccine efficacy?

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More than 188 million people have been infected with COVID-19 and over four million have died from it, according to data from the World Health Organization (WHO).

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The coronavirus has constantly evolved through mutation, causing new variants to emerge. Multiple variants of the virus have already been documented since the pandemic’s onset as the it continues to infect and pass on from one individual to another.

The dominant variant at the moment is the highly contagious Delta strain of COVID-19. New and more contagious variants of the coronavirus have been a concern for many as they could potentially pose a threat to vaccine efficacy.

Several COVID-19 vaccines have now been approved for emergency use after demonstrating their safety and effectiveness. As of July 14, over 3.4 billion vaccine doses had been administered across the world, according to the WHO, accounting for at least 990 million people who are fully vaccinated against the virus.

Having overcome the first hurdle of immunization and vaccine deliveries, the question that remains is: how long will this immunity last in the face of new variants?

How vaccines work

When the virus that causes COVID-19 invades our bodies, it attacks and then multiplies, causing an infection. Our immune system uses an array of tools to then fight off this infection, such as with red blood cells carrying vital oxygen to tissues and organs, and white blood cells acting as the key shield against infecting viruses, bacteria, fungus and other microorganisms.

In this file photo taken on April 9, 2021, a nurse prepares a dose of the Pfizer/BioNTech Covid-19 vaccine at a vaccination centre set up at the exhibition hall in Nantes, western France. There is no need for the moment to offer a third dose of vaccine against Covid-19 to the entire population, apart from the most vulnerable and the oldest, for lack of available data, said the French High Authority for Health (HAS) on July 16, 2021. (AFP)
In this file photo taken on April 9, 2021, a nurse prepares a dose of the Pfizer/BioNTech Covid-19 vaccine at a vaccination centre set up at the exhibition hall in Nantes, western France. There is no need for the moment to offer a third dose of vaccine against Covid-19 to the entire population, apart from the most vulnerable and the oldest, for lack of available data, said the French High Authority for Health (HAS) on July 16, 2021. (AFP)

All vaccines work by exposing the body to molecules from the target pathogen to trigger an immune response, according to the global vaccine alliance GAVI.

When a vaccine is introduced into a person’s body it offers them protection by providing the body with a supply of memory to help it remember how to fight off the same virus – if they were to ever get infected in the future.

It usually takes two to three weeks for the body to begin to produce its defense mechanism after being vaccinated, according to the Center for Disease Control and Prevention (CDC).

Why vaccination is so important

Peoples’ knowledge of vaccines has increased considerably throughout the many months of the pandemic. This is unlikely to change because everyone wants to keep pace with the best ways to protect themselves from COVID-19. New technologies and medicines are likely in the world’s long, continuous fight against COVID-19.

“We still don’t have all the answers and need more research, but it’s urgent for people to get vaccinated as soon as possible if they can in order to protect themselves, their families and loved ones from these new variants,” Project HOPE’s Chiefly Health Officer and former CDC Director of Global Health, Dr. Tom Kenyon, told Al Arabiya English.

“The longer it takes to vaccinate everyone, the more opportunity there is for the virus to mutate, and the more the virus mutates, the greater the possibility of creating variants that are more contagious, make us sicker, and are able to evade the immunity we develop when we are vaccinated,” he added.

Speed of access to COVID-19 vaccines is so critical, GAVI reported, adding that countries with surplus doses will need to donate the shots to lower-income countries. Any delay in access in these countries will increase the risk of virus transmission hence causing the pandemic to proceed and even worsen.

 A woman walks past an information sign amid the outbreak of the coronavirus disease (COVID-19) in Bolton, Britain, May 17, 2021. (File Photo: Reuters)
A woman walks past an information sign amid the outbreak of the coronavirus disease (COVID-19) in Bolton, Britain, May 17, 2021. (File Photo: Reuters)

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We are in the midst of the world’s fastest and largest vaccine deployment so the duration of immunity will be important in determining when we will be able to put this phase of the pandemic behind us. Because if the duration is shorter, it would give health authorities less time to protect enough people from the virus by limiting its circulation.

Effectiveness of vaccines

Pfizer recently confirmed that immunity from their mRNA-based vaccine was 91.3 percent effective, six months after the second dose, GAVI reported. Another widely available mRNA jab, Moderna’s vaccine, showed 94 percent effectiveness six months following the second dose.

“This six month marker is an important milestone and both manufacturers will continue to monitor the effectiveness of their vaccines as the months roll by,” a statement on GAVI’s website read.

A shipment of COVID-19 vaccines distributed by the COVAX Facility arrives in Abidjan, Ivory Coast, Friday Feb. 25, 2021. (AP)
A shipment of COVID-19 vaccines distributed by the COVAX Facility arrives in Abidjan, Ivory Coast, Friday Feb. 25, 2021. (AP)

Public Health England (PHE) also conducted a study on vaccine efficacy against the Alpha variant and found that the Pfizer and AstraZeneca vaccines were both effective in reducing the need for hospitalization upon infection with COVID-19, accounting for 96 and 92 percent effectiveness, respectively.

However, since the results of the analysis were against hospitalization from the Alpha variant, more work is being done to establish the level of protection against mortality from the Delta strain, the PHE study reported.

They also published an analysis in December 2020 which showed that one dose was 17 percent less effective at preventing symptomatic illness from the Delta strain (compared to Alpha), adding that there was a minor difference after two doses were administered.

Booster shots

Vaccine companies have been exploring the idea of booster shots to provide better protection, if needed, in the future.

The Pfizer-BioNTech vaccine’s efficacy, previously at 93 percent, was deemed less effective in a statement released by the partners, citing Israel health ministry data on the matter.

The data revealed that the vaccine was only around 64 percent effective at protecting against breakthrough infections.

However, according to the New York Times, this data has not been peer-reviewed and may be more complex due to a number of variables, one of them being that the Delta variant was not yet widespread at the time.

”Today our vaccines seem to remain effective against COVID-19 and new variants. Tomorrow that may not be the case, which would be disastrous,” Dr. Kenyon told Al Arabiya English.

“So far, US government scientists have not seen any evidence of waning immunity with current vaccines and so no decision has been made to administer booster shots at this time,” Dr. Kenyon said.

“Existing vaccines provide excellent protection and the risk of serious side effects may increase unnecessarily if people routinely receive a third dose. There may be certain groups, such as the elderly who don’t respond as well to vaccines and are at high risk for severe infection, where the benefits of a third dose outweigh the risks.”

Professor at the University of Pennsylvania and member of the Food and Drug Administration (FDA) vaccine advisory panel, Dr. Paul A. Offit, told the New York Times that while studying the safety and effectiveness of booster shots is important, the current evidence shows that the available vaccines work well against the Delta and other variants.

“Roughly 99 percent of people who are hospitalized and killed by this virus are unvaccinated,” said Dr. Offit. ”You’re not really trying to prevent asymptomatic or mild symptoms. You’re trying to keep people out of the hospital and out of the morgue. It’s a goal we’ve met remarkably well.”

However, due to vaccine supply issues and a large number of unvaccinated people in the world, namely in developing countries, experts told the New York Times that it is shortsighted to administer additional doses to people in wealthy nations who are already fully vaccinated and looking for extra protection.

”The priority now must be to vaccinate those who have received no doses and protection,” Tedros Adhanom Ghebreyesus, the WHO director general, said in a press conference recently, in a push-back against Pfizer’s announcement on plans to authorize a booster shot.

It is clear that the medical community is in two minds about booster shots to protect against COVID-19. Vaccine supply issues and a large amount of unvaccinated people amid the contagious Delta variant have put the topic of booster shots on the backburner so that experts can do more to curb the virus’ spread and mitigate the risk of death.

Read more:

Pfizer, Moderna vaccines could protect against COVID-19 for years: Study

Explainer: The difference between COVID-19 mRNA and Adenovirus-vector vaccines

UK researchers discover new way to make future COVID-19 vaccines more effective