The most common question I receive from patients who have recently recovered from COVID is : ‘Doc, can I get it again?’. Infected individuals are hopeful of never having to worry about COVID-19 again. However, the significance of this question is far larger than those who are asking may realise. If recovery from COVID confers permanent immunity, the course of this pandemic will be simpler and more manageable than it would if immunity wanes over time.
Now that millions of individuals are months past their COVID infections, studies have begun to unravel the complexity of the body’s response to the virus, allowing us to understand how immunity to COVID-19 works and how this pandemic may end.
A study released in July 2020 from the King’s College in London came to the scary conclusion that ‘COVID-19 immunity from antibodies lasts only a few months.’ Antibodies are proteins produced by the immune system that stick to viruses and neutralise them before they can cause illness.
The study followed 65 COVID-19 positive patients for 94 days and showed that antibody levels peak at 20-30 days after infection and then steadily fall over 3 months. It has been postulated that this drop in antibodies may reduce the chances of herd immunity ever developing. There are also concerns that it may decrease the chances of a vaccine working, and that if you recover from COVID-19, you are at risk of catching it again, 3 months later.
However, antibodies are only one facet of immunity. The human body has special cells called Killer T-cells, which identify viruses once they have already entered cells, where they are no longer visible to antibodies. As their name implies, Killer T-cells destroy these viruses. Memory B-cells also have a role to play. These are special cells hidden in the spleen and lymph nodes that remember the shape of previously encountered viruses and quickly make new antibodies if the virus is encountered by the body again. This colourful immune army may ensure a milder and shorter duration of illness, if one can indeed get COVID a second time.
The picture of diminishing antibodies to COVID-19 is typical of other Coronaviruses we have encountered before, which explains why people can repeatedly contract colds caused by Coronaviruses. But the more formidable killer T-cells being more permanent- is equally typical in other Coronaviruses, including SARS and MERS. This is good news for long term immunity.
If COVID antibodies are temporary, can we still make a vaccine that offers long term immunity?
A vaccine is an agent that teaches the immune system to create a response that will protect the body against a virus that it may encounter in the future. The diminishing antibodies to the SARS-COV-2 virus make vaccine development challenging – but not impossible. 154 vaccine trials are already underway across the globe. 6 of these are already at phase 3 (out of 5 phases). The complexities in the immune response to COVID-19, may mean that more than one dose of vaccine will be needed, or that there may be different vaccine schedules for different types of patients.
Michael Mina, an epidemiologist of Harvard medical school commented that ‘reinfections may become normal – but that doesn’t mean herd immunity isn’t achievable.’ He comments that second and third infections of COVID may just be milder. In essence, we would develop herd immunity to the ‘severe’ SARS-COV-2 virus.
But what if all fails? No vaccine and no herd immunity. Is the current situation our new normal?
Absolutely not. Giannitsarou et al. (2020) recently published an encouraging study that considers the possibility of temporary immunity and ongoing waves of infection. With this picture of COVID-19 becoming ongoing (endemic), social distancing, lockdowns and mask wearing are likely to become ongoing too. However, the research points out that if COVID becomes less lethal, lockdown measures are likely to become far less strict too.
Furthermore, human beings and societies adapt. Individuals, organisations and governments may exercise more caution where it is needed, and become more flexible in terms of schooling, business and even leisure & travel.
In future, we may live in a society in which COVID-19 continues to exist but we have already come so far in terms of management of severe COVID and will in all likelihood continue to fine tune this. Our children will return to school , and we will be able to interact with outsiders and establish new connections.
The take home point is that even if we cannot be certain whether or not long term immunity to COVID-19 exists, whether or not there will be a vaccine one day or whether or not herd immunity is even a possibility, the current situation will not continue indefinitely. So do not allow your current restrictions to cloud your aspirations of future freedom. You may not know exactly what “opening up” is going to look like, but be ready to embrace it when it’s time to unlock that front gate and go out into the world again….it may be far sooner than you think.
