Can I Be Immune to Covid-19?

Aside from durability, not all vaccines have complete protection, for example, the annual flu shot ranges in effectiveness and works better for children than for the rest of the population. In 2019, it was less than 50% effective in preventing the flu, but there were still major benefits.

While our hopes for a return to a ’ normal world” lie in a vaccine primarily and progress is being made in that regard with over 150 vaccines being investigated worldwide – we still have major questions that remain unanswered.

What is immunity?

When the general public uses the term immunity – it is thought of as an almost absolute protection. However in many cases immunity is anything but absolute. The flu vaccine, for example reduces the risk of more severe disease for example rather than infer absolute immunity.

How does immunity work?

In the case of COVID-19 the main mechanism is through the production of antibodies. But it should be noted that one study has found that as many as 8.5% of those infected had zero detectable antibodies. Additionally it is thought as survivors tend to be younger – there are also cell-mediated arms of the immune system that can neutralize the virus through white blood cells and cytokines.

As Charles Cairns, the dean of Drexel University College of Medicine has said: “those who have inflammation mount an immune response that’s more detectable and potentially more robust.” This further points to the potential importance of cell-mediated immune response in the case coronavirus.

How long does immunity last?

We do not know yet. However we do know of cases of patients who had a recurrent infection with COVID-19 and we also know that some other coronavirus infections confer only temporary immunity, in some cases as few as a few months. More data is required.

What factors affect immunity?

Essentially the level and duration of immunity from an infectious disease are highly correlated with the severity and duration of the immune response to the infection. As such infections with more severe symptoms tend to a stronger immune response thus inferring a higher level and duration of immunity. Conversely, mild or asymptomatic cases lead to generally lower antibody levels and thus potentially lower levels of, and duration of immunity. However we do not yet know if that is in fact valid for COVID-19.

What does immunity data imply re a potential vaccine?

Simply said – there is insufficient data to answer this with any degree of certainty.

“Obviously, a vaccine that works 100% of the time would be ideal, but that is not realistic,” said Dr. John Mascola, director of the National Institutes of Health Vaccine Research Center.

The level of response to a vaccine may vary from a slight reduction in severity of the disease in some populations or people, to a very high level of protection in most individuals. With so many vaccines in development it is likely that the results will also vary.

Until we have the results of phase III trials which will measure the actual efficacy of the vaccine we won’t know for sure for any individual vaccine. We will thereafter have a better understanding of the relationship and degree thereof between antibody levels and immunity.

It should be noted however than in the case of the influenza vaccine which can have an effectiveness of only 50% in preventing the flu – still confers major benefits not only to those protected but the community as a whole by decreasing the number of infections, and deaths while also decreasing the number of those who become severely ill and require hospitalization, intubation and admission to intensive care.

How do the different vaccines being investigated work?

Different approaches are being used by various institutions to create a COVID-19 vaccine. The group from Oxford and its partner AstraZeneca for example are using the more traditional approach of an attenuated virus which is a virus that doesn’t make people sick but infers immunity. Yet others with Moderna and Pfizer being well known examples are using proteins that can “trick the immune system into mounting an effective response against future infection.”

Once there is a vaccine – who should get it?

Again we don’t know yet until results from the trials come in at the very least. However if as may be the case – previous infection with COVID-19 does not infer as strong or as long a level of immunity – then most people would likely be recommended to be vaccinated.

Additionally like in the case of the flu vaccine, a coronavirus vaccine might also work better for certain sub-groups.

What if the COVID-19 virus mutates?

The structure and biology of this virus is such that it is covered in tiny spikes called surface proteins. Most experts indicate that most vaccines being developed currently are likely to work into the future as sufficient mutation to incur lack of efficacy is unlikely – though a finite possibility does exist.

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