Being up to date on COVID-19 vaccines means you have had three or four doses of the same vaccine at this time. Current reinforcements are the same formulations as the first authorized injections, based on the original strain of coronavirus that emerged in late 2019. They still protect against severe COVID-19, hospitalizations, and deaths.
But as immunity declines over time and new, more contagious variants of SARS-CoV-2 emerge, the world needs a long-term impetus strategy.
I am an immunologist studying immunity to viruses. I was part of the team that helped develop the Moderna and Johnson & Johnson SARS-CoV-2 vaccines and Eli Lilly and AstraZeneca monoclonal antibody therapies.
I am often asked how often, or infrequently, I think people are likely to need COVID-19 booster vaccinations in the future. No one has a crystal ball to see which variant of SARS-CoV-2 will come next or how good future variants will be to evade vaccine immunity. But looking at other respiratory viral enemies that have worried humanity for a while may suggest what the future might hold.
The flu virus is one example. It is endemic in humans, that is, it has not disappeared and continues to cause recurrent seasonal waves of infection in the population. Every year, officials try to predict the best formulation of a flu vaccine to reduce the risk of serious illness.
As SARS-CoV-2 continues to evolve and is likely to become endemic, people may need regular booster injections in the foreseeable future. I suspect that scientists will eventually have to upgrade their COVID-19 vaccine to adopt newer variants, as they do with the flu.
Influenza forecasting, based on careful surveillance
Influenza virus surveillance provides a potential model of how SARS-CoV-2 could be tracked over time. Influenza viruses have caused several pandemics, including the 1918 one that killed about 50 million people worldwide. Every year there are seasonal flu outbreaks and every year officials encourage the public to get vaccinated against the flu.
Every year, health agencies, such as the World Health Organization’s Global Influenza Surveillance and Influenza Response System, make a guess based on the flu strains circulating in the southern hemisphere about which ones have the most chances of circulating in the next flu season in the northern hemisphere. Large-scale vaccine production then begins on selected influenza strains.
Some flu seasons, the vaccine does not turn out to be a great combination with the virus strains that end up circulating more widely. In those years, the vaccine was not so good as to prevent serious illness. Although this prediction process is far from perfect, the field of influenza vaccine has benefited from strong viral surveillance systems and a concerted international effort by public health agencies to prepare. .
Although the details of influenza viruses and SARS-CoV-2 are different, I think the field of COVID-19 should consider adopting similar long-term surveillance systems. Keeping track of which strains are circulating will help researchers update the SARS-CoV-2 vaccine to match up-to-date variants of the coronavirus.
How SARS-CoV-2 has evolved so far
SARS-CoV-2 faces an evolutionary dilemma as it reproduces and spreads from person to person. The virus must maintain its ability to enter human cells through its ear protein, while changing it to allow it to evade vaccine immunity. Vaccines are designed to get your body to recognize a particular ear protein, so the more you change, the more likely it is that the vaccine will be ineffective against the new variant.
Despite these challenges, SARS-CoV-2 and its variants have successfully evolved to be more transmissible and to better evade people’s immune responses. Throughout the COVID-19 pandemic, a new variant of SARS-CoV-2 concern has emerged that has dominated transmission in a series of contagious waves every four to seven months.
Almost like a clock, the D614G variant emerged in the spring of 2020 and surpassed the original strain of the SARS-CoV-2 outbreak. In late 2020 and early 2021, the alpha variant emerged and dominated transmission. By mid-2021, the delta variant surpassed alpha and then dominated transmission until it was displaced by the omicron variant in late 2021.
There is no reason to think that this trend will not continue. In the coming months, the world may see a dominant descendant of the various omicron subvariants. And no doubt a new variant of a non-dominant group of SARS-CoV-2 may emerge, which is how omicron itself was.
Current booster injections are simply additional doses of vaccines based on the long-extinct outbreak of the SARS-CoV-2 virus strain. Coronavirus variants have changed a lot compared to the original virus, which is not a good omen for the continued effectiveness of the vaccine. The idea of tailor-made annual vaccinations, such as the flu vaccine, seems appealing. The problem is that scientists have not yet been able to predict what the next variant of SARS-CoV-2 will be with any degree of confidence.
Planning for the future
Yes, the dominant variants of SARS-CoV-2 in the coming autumn and winter seasons may look different from the omicron subvariants currently circulating. But an upgraded booster that looks more like the current omicron subvariants, along with the immunity people already have since the first vaccines, will likely offer better protection in the future. It may require less frequent magnification, at least as long as omicron underlines continue to dominate.
The Food and Drug Administration will meet in the coming weeks to decide what fall reinforcements should be in time for manufacturers to produce the shots. Vaccine manufacturers like Moderna are currently testing their booster candidates on people and evaluating the immune response against new emerging variants. Test results will likely decide what to use in anticipation of a fall or winter wave.
Another possibility is to target the vaccine enhancement strategy to include universal coronavirus vaccine approaches that already look promising in animal studies. Researchers are working on what is called a universal vaccine that would be effective against multiple strains.
Some focus on chimeric peaks, which fuse parts of the ear of different coronaviruses into a vaccine, to extend protective immunity. Others are experimenting with nanoparticle vaccines that get the immune system to focus on the most vulnerable regions within the coronavirus ear.
These strategies have been shown to prevent SARS-CoV-2 variants that are difficult to stop in laboratory experiments. They also work on animals against the original SARS virus that caused an outbreak in the early 2000s, as well as zoonotic bat coronaviruses that could jump on humans, causing a future outbreak of SARS-CoV-3.
Science has provided multiple safe and effective vaccines that reduce the risk of severe COVID-19. Reformulating reinforcement strategies, whether towards universal-based vaccines or up-to-date vaccines, can help us emerge from the COVID-19 pandemic.
David R. Martinez, Postdoctoral Fellow in Epidemiology, University of North Carolina at Chapel Hill.
This article is republished from The Conversation under a Creative Commons license. Read the original article.