I have been perturbed over the last few weeks to hear some people say that they won’t be getting their second COVID-19 vaccination. Reasons have ranged from “The pandemic is virtually over here now, it’s not necessary” to “I felt ill after my first one so I’m not prepared to feel like that again.” Others have said they feel protected “enough” after their first jab and don’t see the need for a second or that they have had a proven COVID-19 infection and assume they are therefore immune.
Last month the New York Times reported that millions of people in the USA had skipped their second doses with 8% of those who had received Pfizer or Moderna vaccine as their first dose not turning up for their second. That equates to around 5 million people and the trend is not only continuing but worsening. People vaccinated at the very start of the rollout in December 2020 were twice as likely to have their second dose as those vaccinated more recently. (1)
Does missing the second dose really matter?
The short answer is “Yes, it does.”
Two doses embed the immune response into the body’s memory.
Ongoing collection of data worldwide is continually reaching the same conclusion, namely that a single dose of vaccine triggers a weaker immune response than two doses and, although a single dose affords some protection against COVID-19, it is not complete and starts to wane after 12+ weeks. The second dose reinforces the immune response and extends its longevity. It is the second shot that embeds the body’s immune response into the immune system’s memory. (2)
(Only one vaccine has been designed as a one-shot only one and it is that by Johnson & Johnson which is currently being assessed for its blood clotting risks.)
Whilst both vaccines doses contain exactly the same ingredients they “awaken” different parts of the body’s immune system. If we think of the two doses as whole numbers it is as if 2+2=5 or 6 and not 4 – the effect of two doses really is greater than the sum of its individual parts. (3)
Two doses are much more effective than one dose against new variants.
A study in the UK by Imperial College London, Queen Mary University of London and University College London looked at immune responses in healthcare workers who had received one dose of the Pfizer vaccine. They found that only low levels of antibodies to the newer variants were produced after the first dose but much higher levels of protection were afforded by the second dose. (4)
Immunocompromised people are less protected by vaccination.
Millions of people worldwide have weakened immune systems and are vulnerable to infections generally, not just COVID-19. They cannot mount a healthy immune response to infections and also struggle to mount the much needed response to vaccines as well.
Many cancer treatments compromise the immune system, some people can be born with a faulty immune system. Drugs for conditions like Crohn’s disease and rheumatoid arthritis can also weaken the immune system.
For people in this category there are two things that can help them. One is the use of something called monoclonal antibodies which are mass-produced from the antibodies obtained from people who have recovered from infection and are given as infusions into the blood. There are licenced monoclonal antibodies available for COVID-19. However, this is both an expensive and relatively invasive procedure that has to be carried out repeatedly at specialist centres. (5)
The other way immunocompromised people are protected is an obvious one – by not coming into contact with the infection in the first place. In practice this means that the more people who are fully vaccinated the fewer people there are becoming ill and the immunocompromised person is less likely to come into contact with the virus. In other words protecting yourself by having the vaccines also protects others who either cannot have it or are unable to mount the same level of immune response to it. This is the essence of herd immunity where the vast majority are vaccinated and therefore drive the levels of infection down. (6)
What if you have had proven COVID-19 infection?
A study carried out in the USA looked at 260 people who had had COVID-19 infection and then a single dose of the Pfizer vaccine. These people mounted more of an immune response after a single dose than those who had never been infected with COVID-19.
Scientists think it is possible people who have had proven COVID-19 infection may not need a second vaccine dose BUT what remains unclear is how long immunity derived from infection plus one vaccine dose lasts compared to that from two vaccine doses. It may be considerably shorter and the guidance at present is for everybody to have two doses of vaccine irrespective of whether or not they have had COVID-19 itself. (7)
We can see right now what is happening when vaccination rates are low.
The horrific footage coming out of India should act as a warning to all nations that until vaccination rates are high, nowhere is safe. Although the current situation there has multiple causes (click here to read more about India) low vaccination rates have contributed to the escalating crisis.
In January 2021 the pandemic appeared to be in retreat in India and the country was exporting vaccines to other countries. Now, nearly 4,000 people a day are dying from COVID-19 and its horrific second wave shows no sign of abating. (8)
India has currently vaccinated less than 2% of its population and is struggling with severe vaccine shortages. (9)
Countries such as the UK, USA and Israel have rolled out effective vaccination programmes and are seeing their COVID-19 numbers fall dramatically as a result but there is no room for complacency. Any stalling of these programmes will see infection rates rise again.
