Saturday, January 2, 2021

The Moderna Vaccine: End of Pandemic?


The Moderna (mRNA-1273) SARS-CoV-2 vaccine is the second vaccine to receive emergency use authorisation (EUA) by the FDA. Like the Pfizer vaccine, it is also a lipid nanoparticle encapsulated mRNA vaccine, and therefore has the same mechanism of action. Please read about the brief mechanism from the Pfizer vaccine article: I will try to avoid big numbers and statistics in this article. 

Both Moderna and Pfizer vaccines start protecting their recipients 10 days after the first dose, with maximum protection two weeks after the second dose. They both have efficacy ranging from 94-95% in protecting against symptomatic Covid-19. However, studies haven't yet evaluated their role in preventing asymptomatic Covid-19, a substantial missing link. 

Can Covid-19 vaccines mitigate the pandemic? 

People picture vaccines as a way back to normalcy, as before the pandemic; unless these mRNA vaccines' role in controlling asymptomatic SARS-CoV-2 infection is studied, normalcy is out of our reach. The other issues concerning the above question are -

1. Since the phase 3 studies of these vaccines are relatively 'young', we don't have sufficient knowledge about the nature and duration of immunological protection. Animal studies have shown that neutralizing antibodies confer protection and CD4 and CD8 T cells also amplify the immunological response. We don't know how long will the neutralizing antibodies last in our plasma after receiving the vaccine. 

2. With both these vaccines, there is an inevitable study flaw. Vaccine recipients faced more systemic adverse events, such as fever, fatigue, headache, myalgia than the placebo group. These symptoms can also occur with Covid-19. Therefore, it is not unlikely that vaccine recipients could have designated their symptoms to the 'shot', and hesitated to refer themselves to be tested for Covid-19.

3. The third issue is quite popular in the daily news. What if the virus mutates and renders itself 'immune' to the vaccine? Some new strains have come up worldwide, and expectedly, the diaspora has started panicking. People need answers quickly while science takes time. So we cannot rule out the possibility that the virus devises a way to escape from the vaccine-induced immunological response. 

4. Vaccine-associated enhanced disease (VAED). Earlier preclinical studies with SARS and MERS have demonstrated that low-level neutralizing antibodies in the plasma can trigger a severe form of the disease. Both the Moderna and Pfizer vaccines are 100% effective in protecting against severe Covid-19, notwithstanding this fact, the regulatory authorities should monitor these and other vaccine candidates for this adverse event. 

5. Anti-Vaxxers! The anti-vaccine sentiment is appalling, and there have been 'anti-vaccine' protests in many parts of the world, including the US, Germany, Poland, and others. There are numerous fake news and misinformation in social media platforms that misguide people and tarnish their perspective about the vaccines. And this phenomenon has even affected the medical professionals. The healthcare authorities have an onerous task to incite confidence in the general public and safeguard them from misinformation. 


The adverse effect profile of both the vaccines is similar, with the most common being local injection-site reactions. Systemic side effects are more common in the vaccine group and comprise mainly of fatigue and headache. Bell's palsy occurred in three (out of 15,210) vaccine recipients within 28 days of administration. This anecdotal risk would be studied in the planned two-year follow-up. 

Being a physician in the Indian subcontinent, there are various reasons to mistrust this vaccine. Both the mRNA vaccines have been studied primarily in the US population (mainly whites), and we don't have any data on its long-term effects. Recently, I have come across various tweets and posts in my social media feed with the headline - " Doctors and nurses are declining the vaccine." I am unaware of these posts' credibility; however, this isn't false in my experience. Well for what it's worth, we haven't seen a whole lot of polio, diphtheria or smallpox recently. 

Thanks for reading!




No comments:

Post a Comment

This is express yourself space. Where you type create something beautiful! <3
Wondering what do I write? Well...
Tell us something you know better. You are a brilliant mind. Yes, you are! ^__^
Ask about something you don't understand @_@?
Compliment... Say something nice! =D
Be a good critic and correct us if something went wrong :|
Go ahead. Comment all you like here! (:

PS: We have moderated comments to reduce spam. ALL comments that are not spam will be published on the website.