WHAT'S NEW - COVID-19 | Vaccines and Productions

COVID-19 | Vaccines and Productions

27th January 2021

COVID-19 | Vaccines and Productions

We’re getting a lot of questions about vaccines and what they might mean for productions – if someone is vaccinated when can we stop testing?

How soon can they stop masking and distancing? We’re really excited about the vaccines too, but even if all your cast and crew have been vaccinated, had both doses and waited a few weeks for the immune system to catch up, you still can’t relax any of the current precautions, vaccinated or not. Those need to be around for a while yet.

So let’s say your whole cast and crew has been vaccinated. Surely with 95% protection you’re good to go?

No. First, we need to look at where that ‘95% immunity’ figure comes from and what it really means.

Whenever a vaccine is developed, it follows the same path.

  1. Safety: after lab and animal studies the vaccine is given to a small group of people just to make sure it doesn’t behave differently in actual humans and has no unexpected, potentially unsafe outcomes. And there’s a tradition where the scientists tend to use themselves as the first guinea pigs!

  2. Clinical Trials. Enroll a whole bunch of people, give half of them the vaccine, half of them a placebo - but don’t tell them which they’ve had.

  3. Release them into the wild and see what happens – in this case monitor carefully who gets COVID and whether they had the real vaccine or the placebo.
If the vaccine doesn’t work, of the trial participants who subsequently catch COVID you’d expect half to be in the vaccine wing, half in the placebo wing. So let’s look at the Pfizer data.
  • They enrolled about 44,000 people, 22,000 got the vaccine, 22,000 got the placebo.

  • There were 170 cases of COVID-19 observed in the whole group (with onset at least 7 days after the second dose) - 8 cases occurred in vaccine recipients, and 162 in placebo recipients, which is how they come up with 95% vaccine efficacy. If the vaccine hadn’t worked you’d expect that split to be (about) 85/85, not 8/162.
So the vaccine was 95% protective across the whole group – which is a bit different to it being 95% protective in an individual.

At individual level there’s lots of factors at play. Some people will get a stronger / more protective response to a specific vaccine, some less so. Plus some people’s immune systems are generally less robust due to disease, age, genetics and other factors.

Also the vaccine might give you a level of protection where you still get infected – but the disease progression is very mild or asymptomatic – which doesn’t necessarily stop you spreading it.

There are other considerations too; the prevalence of the virus in the community, how many or few people stick to the dosing schedule, was the vaccine was stored at the correct temperature… all these have an impact on how effective the shot might be in an individual.

For all these reasons a vaccine’s real-world effectiveness tends to be slightly lower than its reported efficacy - but the point is effectiveness is at the community / population level, and there can be quite a bit of variability at an individual level.

In a perfect world, vaccines induce ‘sterilising’ immunity, which means preventing infection: if the virus enters a person’s body the immune system reacts so quickly that the virus doesn’t get the chance to replicate.

In reality, most vaccines don’t provide this level of immunity but they do prevent disease and – often - transmission of the disease from one person to another. We don’t know yet whether any of the COVID vaccines being developed will cause sterilising immunity or whether they’ll prevent transmission. So another reason it will still be necessary to wear masks and continue social distancing for quite some time after people begin receiving vaccines.

How Much Immunity Will We Get?

We won’t know that for a while – the priority has been to get the vaccine out to reduce mortality and only long-term, post-immunisation monitoring will tell us whether the initial vaccine doses are sufficient or further boosters are needed. But currently the numbers remain encouraging for how long immunity might last.

Also the mRNA vaccines do seem to be more protective against future infections than the immunity that arises from already having recovered from COVID. Both the Pfizer and the Moderna vaccines resulted in higher concentrations of ‘neutralising’ antibodies than in people who had recovered from having COVID (neutralising antibodies are the ones that block an infection entirely when they bind to the spike protein of the virus, and the more you have the less likely you are to develop an infection that you can transmit to others.


All viruses mutate. This one not so much as flu, but it does mutate. It’s highly unlikely a mutant will arise that would render the current vaccines totally ineffective. It might reduce the percentage efficacy a bit though.

But the great thing about the mRNA vaccines is that once you have the genetic sequence of the variant (which takes a day or so in the lab) you can manufacture a new vaccine in a few days. It’s not like flu vaccines which are still mostly grown in hens’ eggs which takes months to do at scale.

Will the Vaccine Make Me Test Positive?

No. the vaccine won’t cause you to test positive on PCR, LAMP or antigen tests. However you may test positive for antibodies – which means the vaccine is working.

Can We Stop Masking Yet?

No. There are very good reasons we need to continue to be diligent post-vaccination.
  1. As we’ve seen, 95% effectiveness in reducing the risk of contracting the disease means that about 5% of vaccinations (and likely higher) don’t produce an effective immune response. And because COVID-19 is still widespread, someone who didn’t get an appropriate immune response from the vaccine may be vulnerable to the disease.

  2. We don’t know if these vaccines prevent asymptomatic carriers - someone who carries the virus but shows no symptoms. It is possible that someone who has had the vaccine could still transmit the disease to someone who is not immune.

  3. There is some risk that the vaccines lose effectiveness over time, whether it’s months or years, or that a new mutation arises that could avoid the immune response conferred by the vaccine. It will take time to determine if there is long-term COVID-19 vaccine effectiveness. Also we haven’t developed long-term immunity to the four other coronaviruses that cause colds that have been infecting us for centuries.
Until we achieve herd immunity we are all at risk, and having the vaccine does not confer a free pass to do whatever we want. And we’re a long way off herd immunity. Until we get an all-clear from public health experts that we have achieved a community level of immunity, masking, distancing, hygiene and the other measures we know work are here to stay.


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