The Contagious SARSCOV2 Virus and its Place in the Coronavirus Family
A vaccine will need to elicit enduring high-level immunity, but viruses within the coronavirus family often fail to generate such immunity. Here is a helpful graph illustrating antibody responses to SARS-CoV-2. Many individuals do not produce a robust IgM response, and the IgG response notably diminishes after only two months. This is in line with other human coronaviruses that evoke an immune response, but it tends to wane, enabling the same virus to re-infect us in one or two years.
The host-pathogen interaction of human coronaviruses is discussed in the Annual Review of Microbiology. Experience with veterinary vaccines for coronaviruses is also not ideal. There are economically significant coronaviruses that infect farm animals, and scientists have been endeavoring to develop effective vaccines for these viruses for decades.
Most of These Vaccines Have Failed
COVID-19 in veterinary medicine, a health perspective: what animal coronaviruses have taught us. The problem is that SARSCOV2 is a highly contagious virus of the coronavirus family. While initial estimates for the R0 were in the range of 2.5, recent estimates suggest it is in the range of 3 to 5, and some people really seem to be super-spreaders who shed large amounts of virus.
That means a vaccine will have to be quite effective if it is going to stop the spread of SARSCOV2 and other coronavirus family microorganisms. Polio, measles, and smallpox vaccines are really remarkable drugs that induce long-lasting high-level immunity, but not all vaccines work that well. Seasonal flu vaccines are only 50% effective, which means there is still a 1 in 2 chance of getting the flu even if you got the vaccine.
The Challenge of Combatting SARSCOV2 and Other Viruses in the Coronavirus Family
It is important to note that SARSCOV2 belongs to the coronavirus family, which also includes other viruses that have caused epidemics and pandemics in the past, such as SARS and MERS. The unique characteristics of the coronavirus family, such as their ability to rapidly mutate and evade the immune system, pose significant challenges for developing effective vaccines and antivirals. While progress has been made in understanding the biology of these viruses and developing treatments, continued research and investment is needed to combat the current pandemic and prepare for potential future outbreaks.
Other Vaccines Are Saving Lives
But still, flu vaccines still save thousands of lives. That’s because the flu is not as contagious, R0 of 1.4-1.7 So even if only half the population takes the flu vaccine and it only works half the time, we are still reducing effective infectivity to a range of 1 to 1.3, which means the flu virus spreads much less rapidly, far fewer people get infected, and lives are saved.
On the other hand, the R0 for SARSCOV2 is 3 to 5, so a vaccine that fades to 50% effectiveness would still leave infectivity at 1.5 to 2.5. And that assumes 100% vaccination. If only half the population accepts vaccination, infectivity would be 2.3 to 3.8. That’s pretty contagious. In short, we all expect we develop a highly effective vaccine quickly, but the biology of any coronavirus family virus and the history of veterinary vaccines suggests it may be a difficult task.
Antivirals and Social Distancing
In order to combat viruses within the coronavirus family, it is imperative that we persist in the development of antivirals, as well as prepare for prolonged periods of social distancing. In summary, combatting viruses in the coronavirus family requires a multi-faceted approach that includes developing effective antivirals, implementing professional social distancing measures, and researching and producing vaccines. Antivirals specifically target and inhibit viral replication, while social distancing measures slow the spread of the virus. A vaccine may not entirely prevent infection, but it could still reduce the severity of the disease.
It is important to continue investing in the development and production of vaccines and antivirals, as well as ensuring their accessibility to those who need them. While there is progress being made, it is important to remain cautious and recognize that medical research does not guarantee success. However, even a vaccine that only alleviates severe disease and requires an annual booster would be a significant achievement in the fight against the pandemic.
Author: Dr. Ulises Bacilio
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