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Vaccine questions answered

Prof Claire Hopkins answered our questions

Chrissi recently spoke with Professor Claire Hopkins about the new Covid vaccines and their potential impact on people with smell loss. 

This was a great opportunity to get some information specifically related to smell loss. Before they started, Prof Hopkins did make a disclaimer: “I’m an ENT surgeon who is actively involved in research in the ENT arena; but I’m not a virologist, I’m not a specialist in infectious diseases and epidemiology. So I can answer based on my interpretations of the data that’s publicly available.

What I would advise for myself and my family – I’m a mother of two school-aged children and I’ve got an elderly mother – my answer will be as much from that perspective as it will an ENT scientist.”

We’ve shared some edited highlights here, but you can watch the full 18 minute Q&A with Professor Hopkins on our YouTube channel.

Could one of the ‘mild symptoms’ associated with getting the vaccine be further loss of smell?

When you have a mild, flu-like illness after having the vaccine – it’s not a mild version of the infection that you’re being vaccinated against. The symptoms are just described like a ‘mild flu-like illness’. People aren’t getting a mild dose of Covid, and that’s really important.

When we think about the mechanism behind Covid-related smell loss, we know that in a normal case where you catch Covid, you inhale the virus particles through the nose, and they bind to cells in the olfactory cleft. They cause the damage by damaging the olfactory epithelium.

When you get a vaccine, you basically get an extracted component of the virus - in most cases, including this one, an area called the ‘spike protein’. This is part of the virus that the immune system needs to generate the antibodies and memory cells that will prepare the body for the next infection. With the vaccine, you’re only getting that part. The vaccine is given into a muscle, and that’s not going to travel to the nose. I think that the chance of the vaccine causing loss of smell or having it make the current symptoms worse simply isn’t real.

What risks are associated with catching the virus again?

People who have persistent smell loss on its own: we are seeing good signs of recovery in that group. And so we understand why anyone in that group might be hesitant to try anything that might risk a deterioration. My worry would be that, for this group, a second exposure to Covid might cause further damage to the olfactory neurons – that might be even worse for long-term recovery. I would be much more worried about a ‘natural’ second infection than about the impact of the vaccine.

There is a huge fear of the unknown about the vaccine. But if we focus on what we know about Covid, the risk of death is about 1 in 80 people, so it’s a significant risk. Additionally, there are people that have been left with life-changing consequences of the infection, as well as people with so-called ‘milder cases’ that have left people with life-altering smell loss. To risk another infection is to risk all of those things.

There are many unknowns about the vaccine – but it has been trialled in thousands of patients with very few side effects found.

So, if you get Covid, you have a 50 percent chance of losing your sense of smell again versus an almost non-existent risk to your sense of smell with the vaccine. I can’t imagine a mechanism whereby the vaccine would affect your sense of smell.

We have to weigh up what we do know against the fear of the unknown.

Will people who have had Covid before have priority in getting the vaccine?

I think that people should be offered the vaccine based on age, comorbidity or risk of exposure, regardless of whether they’ve had Covid or not before – I don’t think that a prior infection with Covid should play into that.

Has the vaccine trial been rushed?

I’ve seen this come up in posts a lot – people are very worried about whether these vaccine trials have been rushed, with lots of comments claiming that vaccines normally take years to develop.

I think it’s really important to explain how trials work. The speed at which you can develop and trial a new drug depends on many things – but depends most importantly on: the frequency of the disease or condition you’re studying; the frequency of the intervention; what you’re trying to change; the willingness of people to take part in the trials; the expertise of the trial teams; and how much money you’re willing to throw at it.

It normally takes years because all of those things are limiting. For example, one trial I was involved with for nasal polyps took us three years to recruit 400 patients, despite some of the best expertise in the world. It was limited by all of the factors above. However, even with just 400 patients (only 200 of whom got the drug, with the others receiving a placebo) it was still approved for use by the FDA – showing how few trial participants you usually need for drug approval.

If we look at the Astra Zeneca COVID vaccine trial for example, there were 43,000 participants – with 100,000 people signing up via the UK Government website to express an interest in taking part in a trial. That’s why we’ve been able to get these trials done so quickly – not because it’s been rushed, but because people turned up in their thousands to take part in these trials. There was a huge amount of money thrown at it, and every team in the world involved in vaccine development came together and collaborated.

None of the normal safety steps have been done any more quickly, it’s just that there has been so much effort put into this, that they were able to get to the end result much more quickly.

That’s not to say this is the definitive answer. Of the 43,000 patients who took part in that trial, none had serious adverse side effects. So we can say that the risk of a serious adverse event is less than 1 in 20,000 – but it’s not going to be absolutely non-existent. There is no treatment that is 100 percent safe and indeed nothing that we do in life is ever 100 percent safe.

There have been a couple of reports of patients with life-threatening allergies (requiring them to carry an epi-pen) who have experienced an allergic reaction to the vaccine. We are going to see some adverse events reported, but we have to think about how common these are.

All I can really do is encourage you not to read the rumours and scare stories, and really focus on what an incredible achievement this is, and what a possibility it offers us to go about our daily lives without that constant fear of (re)infection.

Professor Hopkins, will you be getting the vaccine?

I can’t wait!

I saw the vaccination pods at Guy’s Hospital yesterday and was really excited, and I was really sad that I wasn’t down there with them.

I’ve gone to work scared for the last nine months – the first couple of months, it was horrendous. I was scared not just for myself, but about bringing Covid back and infecting my family.

I think the vaccine is one of the most remarkable achievements of modern medicine. I’m really proud to be a part of it and can’t wait to get it.


You can watch the full webinar at

December 18, 2020