Dear Editor,
By now most would have heard of the Delta variant or lineage B.1.617.2 first detected in Maharashtra (India) in December 2020. Initially it was not seen as anything special but then in April 2021 with almost 30,000 cases of infection reported daily in Delhi, it became a matter of grave concern. From Delhi it continued to spread and is now likely to become the dominant form in the world as it accounts for 90% of infections in the UK; consequently, their re-opening plans were delayed. A surge in cases in Lisbon (Portugal) caused the Portuguese government to re-impose a three-day travel ban between the city and the rest of the country. Andrea Ammon (Director of the European Centre for Disease Prevention and Control) said that, “It is very likely that the Delta variant will circulate extensively during the summer, particularly among younger individuals that are not targeted for vaccination” and “…that by the end of August it will represent 90 percent of new cases in the EU.” It is also thought to cause surges in Indonesia, Russia and other countries and is on the rise in North America. Israel, with 60% of its population fully vaccinated, is reinstating its indoor mask mandate due a steep rise in cases attributed to it.
Variants arise as the virus mutates naturally. Every time a virus replicates during infection there is a chance it won’t copy itself correctly. These typos are present in the new copies of itself as they move on to infect others. Some of these ‘mistakes’ appear, some disappear and some persist; some are harmless while some can increase contagiousness or allow the virus to escape our immune system’s protection/antibody neutralization. The variants of concern (VOC), including the Delta variant, have different combinations of mutations which can have one or more of the following properties: more contagious, more virulent and, vaccines, diagnostics, therapeutics and public health measures show a reduction in effectiveness against them.
Many of these troublesome mutations are found on the Spike (S) protein (protrudes from the surface of the virus). The S protein binding to our cells allows virus entry and is a main target for vaccines and treatments. All vaccines in use are based on creating or using a form of this S protein. For example, both the Oxford-AstraZeneca and Sputnik V vaccines, adenoviral vector vaccines, comprise a gene with instructions for making the S protein in our bodies. When our bodies see this protein, an immune response occurs as if you were infected with the virus; antibodies – defense molecules that can neutralize the virus – are produced without us getting infected as the infectious genetic material of the virus is not present, just the S protein. So if vaccines are based on the original form of the S protein but we’re infected with a virus with a new mutated S protein, then the neutralizing antibodies produced after vaccination may not neutralize the virus or not as effectively since a mutation may change the shape of the S protein thereby altering the binding strength of neutralizing antibodies (antibodies we produce from vaccination are specific to the virus, binds to it and prevents it from getting into our cells thereby neutralizing it). This of course depends on the mutations on the variant in question.
Ongoing research suggests the Delta variant possesses about fifteen mutations that enables more efficient entry into our cells thereby making it more transmissible than any other VOC currently. Studies suggest that its mutations allow it to escape neutralizing antibodies which impact vaccines’ efficacy (vaccination induces our immune system to produce these protective antibodies). Research also suggests that these mutations result in stronger binding of the S protein to our cells and faster splitting of the S protein into the form that infects our cells. There is a lot researchers are still finding out but what is definitely known is that one vaccine dose is not good enough, we need two for protection and we need protection as soon as possible so as not to allow the virus room to evolve into an even worse form.
To prevent emergence of worse forms we need population immunity which means most people need to get vaccinated. That’s it. There is no other way to force it into non-existence. Natural immunity does not cut it. This is best exemplified by Brazil where many, prematurely, thought they had acquired ‘herd immunity’ naturally. There were so many people infected and sick with COVID-19 in Manaus – 70% or more of their population – that they thought they had achieved herd immunity (naturally) by fall 2020. We know the story. They were wrong, a new surge in cases was seen in December 2020, daily hospital admissions grew which eventually overwhelmed the health care system and a crisis followed. This new wave involved people who had COVID-19 previously becoming re-infected and local scientists attributed the situation there, mainly, due to a worse form of the virus emerging and dominating (the P.1 or Gamma variant). The health ministry recently declared that their situation is critical (once again) as they hit 500,000 deaths (the second highest in the world) and leaders are being accused of prioritizing and promoting unproven treatments ahead of vaccination (less than 20% of their population is fully vaccinated). The Gamma variant has eleven key mutations which research suggests change the shape of the S protein on the surface of the virus in a way that makes it more difficult for it to be neutralized with antibodies and so like the Delta variant, two vaccines doses are needed for protection.
Clearly variants can undermine progress made with vaccination campaigns. Modifying vaccines to target variants may be fast but the modified form needs to go through three phases of clinical trials again and results reviewed by regulatory bodies. This takes time so we need to make the most of the vaccines we have available now, we need to get immune protection at community and population levels as soon as possible. We need most vaccinated to suppress the virus. So, get vaccinated!
Sincerely,
Jacquelyn Jhingree, PhD.
