What we can do to protect ourselves from new COVID-19 strains?

In the United Kingdom, Christmas is usually a joyful time, providing light and cheer in the harsh depths of winter. Last year, though, was a different scene, as a seemingly more virulent COVID-19 variant sprung up just before the festivities. First detected in September, it grew to represent a quarter of infection cases by November, reaching nearly two-thirds by mid-December.¹

The timing of this COVID-19 variant was unfortunate, but not a surprise to immunologists. As viruses replicate, they naturally acquire changes to their basic genetic information. Most of these changes are a dead end for the virus, or don’t affect how dangerous it is, but occasionally some changes emerge that make the virus stronger. The more people infected, the higher the chance that deadly variants and strains emerge. In the 1918 influenza pandemic, for example, around 80% of the reported illnesses and fatalities were attributable to the second wave.²

With a tendency to mutate being a hallmark of any pathogen, what can we do to protect ourselves from the threat of more deadly COVID-19 strains? Immunologist Dr Larisa Labzin from the University of Queensland says there are various things to consider.

Vaccinate fully and quickly

As the new UK variant raged through the population, government made a tough decision: to inoculate more people with just one dose of the Pfizer vaccine by delaying administration of the second dose.

The gamble was made swiftly and without the aid of clinical data. Pfizer had recommended that a second dose of the vaccine be administered within three weeks of the first, to achieve its maximum efficacy rate of 95%, as demonstrated in clinical trials.³ However, with a single dose offering around 52% protection,⁴ the government thought a wider rollout of initial doses could lessen the demand for acute care, at a time when resources were stretched.

Dr Labzin said this approach can, however, be dangerous. “If people who are given just one dose of the vaccine go back to normal behaviour and are exposed to the virus, that insufficient level of immunity might create just enough ‘selective pressure’ within their body for the virus to fight back and develop mutations,” she said.

“In contrast, administering two vaccine doses induces an immune response strong enough to completely eliminate the virus from the recipient’s body before the virus has a chance to adapt,” she added.

However, sticking to the manufacture guidelines and opting for a quality over quantity approach in the Pfizer vaccine rollout may incur a similar outcome, with mutations also becoming more likely when viruses are given the chance to replicate in large pools of people. If more citizens get at least one jab — and that jab prevents at least some viral transmission — the government’s decision may pay off.

“It’s a really tough call for authorities to make and only time and further data from genomic sequencing and transmissibility studies will confirm if they have made the right choice,” Dr Labzin said.

Prioritising the development of antivirals

In a similar vein, drugs that reduce the time that someone remains sick with the COVID-19 virus can also help prevent mutations, given that some people cannot or will not be vaccinated.

“If we can help people sick with COVID-19 get better more quickly, we are minimising that time for the virus to adapt and grow stronger within their body,” Dr Labzin said.

“There are also new variants of COVID-19 — like the South African variant — which the vaccines aren’t as effective against. Drugs that target the virus directly, like antibiotics do for bacteria, are one of the most promising alternatives.”

At present, no antiviral for COVID-19 has been approved by the TGA, but several are in development. Dr Labzin said it is worth prioritising research into these drugs and making them available for mainstream usage, quickly.

Keeping distance in the meantime

Whilst we wait for everyone to be vaccinated and effective antivirals to be developed, good old-fashioned social distancing, hygiene and PPE are still called for.

This may be especially important for immunocompromised people, who are more prone to long-term illness from COVID-19.⁵ Their bodies are more likely to enter into an ‘arms race’ with the virus, prompting it to evolve into new strains.

Failure to keep cases down through these measures could mean the virus has enough opportunity to escape vaccine-induced immunity, meaning new vaccine formulas need to be continually developed. This is a possibility we are already facing with some of the new South African variants.

“Influenza has grown to be really good at escaping vaccine-induced immunity, which is why we see new variants each year and have to update our vaccines,” Dr Labzin said.

“It is very possible, we could see a similar scenario with COVID-19, with regular updates to our vaccines. This is an eventuality we need to prepare for,” she concluded.

References

1. New coronavirus variant: What do we know? https://www.bbc.com/news/health-55388846.
2. 1918 Pandemic Influenza: Three Waves. https://www.cdc.gov/flu/pandemic-resources/1918-commemoration/three-waves.htm.
3. PFIZER AND BIONTECH CONCLUDE PHASE 3 STUDY OF COVID-19 VACCINE CANDIDATE, MEETING ALL PRIMARY EFFICACY ENDPOINTS - https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-conclude-phase-3-study-covid-19-vaccine.
4. Covid-19: Pfizer vaccine efficacy was 52% after first dose and 95% after second dose, paper shows. https://www.bmj.com/content/371/bmj.m4826.
5. If You Are Immunocompromised, Protect Yourself From COVID-19. https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/immunocompromised.html.

Image credit: ©stock.adobe.com/au/Feydzhet Shabanov