An immunologist explains the Covid-19 vaccine |

Covid-19 vaccine
Photo by Daniel Schludi on Unsplash

Now that some COVID19 vaccines are available and we have options apart from hiding/toughing it out, there are some people who have questions about whether the vaccines are a good choice, what other options we have, when this nightmare will end, etc.

Here are some of the more common questions being asked, and they’re answered by Dr.Chrissie Kaishi Lim, an immunologist with A*STAR.

Don’t vaccines normally take at least 10 years to be certified safe/good?

a. Most of these ~10 year waits are from red tape, paperwork, applying for money for development and getting rejected 90% of the time. This is not hyperbole, but the rough rejection rate of many US grants each round, even from successful world-famous labs. Sadly, this is now the bulk of a scientist’s job.

This year, SARS-CoV-2 work was given priority approvals without such barriers because the world agreed on how quickly we had to act. Yes, that is how much difference it makes when we prioritise scientific development.

b. We managed to act quickly on SARS-CoV-2 based on research in other coronaviruses. For example, we knew to look immediately at spike protein because old work on SARS-1 (2003) and MERS (2012) showed its importance. Some vaccine candidates were also developed at the time which didn’t roll out in time, but we applied their lessons to the COVID19 vaccine candidates. So, really, we began work on SARS-CoV-2 >15 years ago!

c. RNA drug and vaccine technology has been of great interest for at least 10 years for other diseases and active development has happened in the background, although products have not yet been licensed (again, funding/interest).

d. The safety monitoring for the trials was very stringent, as is usual for vaccines compared to drugs. Remember when the whole Oxford/AZ trial of 30,000 people was paused because ONE person reported a severe illness, just so they could figure out if it was from the vaccine or something else? Those high standards have not been compromised for speed. Furthermore, all reactions reported in the vaccine group were also monitored and reported in the placebo group, with similar numbers apart from a bit more temporary soreness/feverishness among vaccine recipients.

The actual science discovery wasn’t rushed, nor was safety. Scientists started building a foundation long before they got credit for it. What we did rush past is a lot of grant money applications, by just supporting the work immediately.

Doesn’t that mean we don’t know if there are long-term side effects from vaccination?

Indeed. To find out, we’ll have to wait another year to let COVID-19 rip through populations, while withholding vaccines which have already shown strong protection and safety for several months.

For most vaccines, side effects happen within days of receiving a dose; it is unlikely for something new to arise only months later. So the calculated risk we are taking now is to slow spread down early, assuming miniscule probability of later effects. Trial participants will still be followed for 2 years, so we will find out as well in 2023.

Should I worry about getting an allergic reaction to the COVID-19 vaccines?

This is the purview of your doctor to counsel based on your individual medical history. Allergic responses do occur to other vaccines, and some who have reported responses to the COVID one had experienced them before for other shots or allergies.

The Pfizer/BioNTech vaccine ingredients are pretty bare bones and a main suspect was polyethylene glycol (PEG2000), which is used to package the active ingredient (mRNA) and is a known allergen.

Importantly, the allergic responses so far to the vaccine do NOT seem linked to common food allergies like eggs, peanuts, shellfish, nor to oral drug allergies. The recommendation is to avoid the vaccine if you’ve had previous allergic reactions to injectable drugs, prior vaccines or PEG2000.

Again, this is for you to work out with your doctor, who can weigh the risk-benefit properly for you based on up-to-date recommendations. Please be assured as well that the trial committees at Pfizer/BioNTech and Moderna are looking hard into why these reactions are happening so they can improve guidelines. It is definitely something the researchers consider important to address and improve.

What about this new variant of COVID19 in the news? Is the vaccine pointless?

We don’t know yet, but some scientists have tried to find out for the past 2 weeks (which is about how long we’ve known about it). Current data suggests that the newly detected variant MAY be more transmissible, but it seems that the antibodies against the “normal” strain block it equally well.

Also, the antibodies and cells that get trained up by vaccines block several different parts of the virus, so it’s usually difficult for one base change to overcome all routes of defence. Overall this means the vaccine should still work, but there are teams still working on a definitive answer.

Wouldn’t developing natural immunity be better than injecting something man-made? We’re just letting our immune responses stay weak.

For SARS-CoV-2 specifically, it seems consistent that “natural” immunity in the way most people mean (i.e. through spontaneous infection) doesn’t last as long as we’d like. Some reinfections are happening within a few months, among high-exposure populations.

So far, models and the trials seem to suggest that more people gain immunity from the vaccine, which also seems longer-lasting. Receiving a vaccine is also, actually, a very natural immune process and strengthens immunity!

Giving a “fake virus” (mRNA, isolated protein, a killed virus) to your immune system to train up on is like taking a martial arts class before actually having a fight: you can pick skills up in a controlled environment like a studio and build the right muscles to tackle the real threat. Getting the real infection first is like meeting a gang boss with no training on those muscles, and being punched to a pulp immediately. Both the vaccine and the virus will activate and train the same processes, same cells and same antibodies to behave as they should – to protect you. The difference is whether you are guaranteed to survive the training/activation.

Which vaccine is best?

Photo by Gustavo Fring from Pexels

Simplified answer: The three famous ones are all great. Get whatever’s available to you. Long, more nuanced answer: The vaccines by Pfizer/BioNTech and Moderna are about 95% effective; Oxford/Astrazeneca’s is between 62 – 90% depending on regimens and interpretation.

Pfizer/BioNTech, Moderna and Oxford/AZ all have excellent safety profiles, and all are loads better than actually getting COVID19 and risking either death, or horrific long COVID where you have difficulty breathing, heart damage, neurological symptoms, etc months (maybe years) after the virus is gone.

There will be specific considerations for individuals, depending for example who the vaccine was tested on (or not tested on) in the trials, allergies, or underlying conditions. This is (again) where you should consult your doctors for risk-benefit.

Singapore has ordered Pfizer/BioNTech, Moderna, and Sinovac ahead of time. This reserves enough doses ahead of time to cover the population quickly when approved. Currently, only Pfizer/BioNTech has been shipped in and approved for administration; if you are in line for the jab right now, that’s what you’re getting!

For those already vaccinated:

Just because you’re vaccinated doesn’t mean everyone else is, or that you’ve stopped carrying the virus from one place to another. We’re also seeing from the early roll-out in the UK and US that receiving the first dose of the vaccine has NOT prevented some healthcare workers from getting COVID19, especially within the first 9-10 days. Please get both doses!

Do your best as well to stick to the same product for both doses – this will be written on your vaccination card/record for reference. While the vaccine will help a LOT, it’s not a magical one-day solution from the sky. We’ll need to keep masking up, washing hands and social distancing for a while, and it’ll still be worth it. You’ll never know whose life you’re saving.