News Archive

Once you’ve had your first dose, just pretend it never happened!

by General Practice Pharmacist Shilpa Patel

I don’t want to put a damper on all this excitement, but I feel the need to make a plea to you all; please continue to wear your mask, to wash your hands regularly, to social distance and to follow the rules. The fact of the matter is that we are no different from where we were a few weeks ago. We still need to protect those with compromised immune systems who cannot be vaccinated as we do not know if we can still be spreaders. There is currently no evidence that having had the vaccine will stop you getting the virus and passing it on. But one thing we do know, is that we are not fully protected after the first dose. Once you’ve had your first dose, I urge you to just pretend it didn’t happen!

I have heard stories about people who have been “hibernating” for almost a year; who now feel invincible! They feel as though they have been let out of prison and I worry that they may take risks they would not have taken before. I fully understand why they feel this way; since they first heard about the approval of the covid vaccine, they have been waiting eagerly to be invited for their covid vaccine appointment. When the day finally arrived, they prepared with anticipation to attend and had some exciting news for family members and friends. “I’m getting my jab today” – It’s the only piece of news they’ve been able to share for months.

They had their vaccine and everything went so smoothly. They anticipated side effects, but only felt a heavy arm, which may even be psychological as they wanted an excuse to not have to do the dishes that evening! It takes a couple of weeks to build immunity, so they waited but started planning. Meanwhile, they saw others starting to meet up again. They had been longing to go out and see loved ones. They have had the vaccine now, so they must be safe? No!

If you’ve only had the first dose then you are most definitely not immune. You cannot start meeting people again. You must not start hugging people again. In fact, if you have not had your booster dose, you might as well assume you have not been vaccinated at all. Although we need to celebrate the fact that these incredibly effective vaccines have been developed and were nothing short of amazing in terms of turnaround, there are already post vaccine covid cases emerging. British, 85-year-old Colin Horseman was among the first people in the world to receive the initial dose of a Covid-19 vaccine – the Pfizer-BioNTech version. After the first dose, according to the Pfizer data, he would have been only 52% immune. He was due to receive the booster to increase this level of immunity, but sadly he died two days prior to his 2nd appointment from Covid-19.

Let me explain very simply how the immune system works when you get vaccinated. When you have your first dose you start producing troops of B cells, which make antibodies. These cells are short-lived. Next, your immune system will activate an army of T cells, these are soldiers and trained to identify a particular pathogen and kill it. Some of these are called memory T cells and these are able to survive for a longer period of time. Some may be ten years and some may be for ever. (This is why some vaccines require a top up every few years and some last a lifetime).

When you are given a your second, booster, dose; there are already enough short-lived B cells, so your body can concentrate on mass production of T cells. After your booster dose, you end up with a larger and stronger army of T cells and memory T cells and to some extent a larger troop of memory B cells.

Let me also remind you that there is controversy over the efficacy of doses. For the pfizer vaccine you may have heard various figures; 52%, 89%, 92% and 95%! Here’s why:

According to Pfizer data published in December 2020, the Pfizer-BioNTech vaccine is roughly 52% effective after the first dose, starting from day 12. The second dose, when given after 21 days is 95% effective at preventing the disease from day 7.

The UK’s Vaccine Committee, the JCVI, decided to calculate the efficacy of the vaccine differently. They only looked at days 15-21. Using this method, the efficacy of the vaccine jumps up to 89%, because it’s not being diluted by the relatively high number of infections before the vaccine begins to have an effect. Taking things even further and only looking at the first seven days after the second dose (days 21-28) – because the second dose might not have kicked in yet by then – it’s 92%.

For the Oxford-AstraZeneca vaccine, there is further controversy; In January, the authors claimed a protection of 64.1% after the first full dose, then 70.4% after the second full dose, yet oddly 90% in people who have had one half dose followed by one full dose.Meanwhile, based on unpublished the UK Vaccine Committee has estimated that, from three weeks until 9-12 weeks after the first injection, the vaccine prevents around 70% of cases of serious disease.

Even once we have had the vaccines and they start preventing illness, we do not know if they also prevent transmission. If we accept that they offer 90%or even 95% protection after the second dose, there’s no way to tell who the 5% will be who don’t respond to the vaccine and will still be at risk for COVID-19. In comparison, the measles vaccine is 97% effective after two doses.

Some pregnant women, people who are allergic and people with chronic medical conditions or low immune system may not be able to have the vaccine.The main concern is that vaccinated people may still be able to become infected without symptoms and then spread it to others who have not been vaccinated yet. If vaccinated people don’t continue to wear a face mask until more people receive their second dose, they could cause the virus to keep circulating.

Achieving herd immunity with safe and effective vaccines makes diseases rarer and saves lives – a high portion of the population needs to be vaccinated with both doses, lowering the overall amount of virus able to spread in the whole population. The proportion of the population that must be vaccinated against COVID-19 to begin inducing herd immunity is not known. This is an important area of research and will likely vary according to the community, the vaccine, the populations prioritized for vaccination, and other factors. The percentage of people who need to be immune in order to achieve herd immunity varies with diseases. For example, herd immunity against measles requires about 95% of a population to be vaccinated. The remaining 5% will be protected by the fact that measles will not spread among those who are vaccinated. For polio, the threshold is about 80%.

Unfortunately, getting vaccinated does not instantly mean we can go back to how life was before. Until we have some level of herd immunity, the vaccine is now just another layer of protection against COVID-19. A couple of weeks after the first dose of the covid vaccine, you do get a partial immune response. A couple of weeks after the second dose, you will reach higher levels of immunity – this is all good news. However, just remember you may be a non-symptomatic spreader and it doesn’t mean you’re immediately protected the minute the needle goes in your arm. So, my advice is to get your jab, then go back home and stay safe. Don’t fool yourself, just pretend you never had the vaccine.

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