Scientists are starting to get a better understanding of the coronavirus which is responsible for COVID-19 – SARS-CoV-2.
At the moment, there are two key unknowns about the new coronavirus which will affect how the pandemic is going to progress.
One is that we don’t know how long immunity lasts for. When patients recover from other coronaviruses which regularly cause common colds – OC43 and HKU1 – they stay immune for less than a year. But immunity against the first SARS virus from 2003 lasts for much longer.
While the antibodies which provide the body’s immune response remain in a person’s blood, to protect against future infection, their strength may reduce over time.
Understanding how long immunity against SARS-CoV-2 lasts matters because this will determine how frequent new outbreaks will be – there could be anything from a seasonal infection to decades-long quiet spells.
Now, scientists and experts may be beginning to get a better picture of the situation. The picture is still imperfect and incomplete, but the experts are filling in gaps in our knowledge.
Researchers at the Peter Doherty Institute for Infection and Immunity in Australia have published a new scientific paper which suggests that those recovering from the new coronavirus show signs of a strong immune response.
Their study was based on one woman who had travelled to Melbourne from Wuhan, China. It showed that, after recovering from the infection, the woman’s antibodies against the virus continued to increase until the time period of the study ended, 20 days after she was first admitted to hospital.
Then, on Tuesday 24 March, scientists studying the virus at the Johns Hopkins University of Applied Physics Laboratory told the Washington Post that the coronavirus does not appear to be mutating significantly as it circulates through the human population. This relative stability suggests that the virus is less likely to become more or less dangerous as it spreads.
If these researchers are right, then it would open up a number of possibilities.
In the short term, if we can expect someone to develop strong immunity to the virus, then there is reason to believe that those who have had the virus would then no longer be infectious. If we can bring the “game changer” antibody tests into play, this would allow us to identify these people so they can return to working in frontline services.
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In the long run, the antibody test would allow us to get a much clearer idea of just how many people have been infected, monitor the development of immunity in populations, and better calculate how fast the virus will continue to spread.
COVID-19 transmission is still being studied, but it is thought that a patient is at their most infectious when excreting virus in ways which may no longer happen once a person is immune.
The main infection route is probably via airborne water droplets. This type of transmission possibly happens while breathing, spitting, coughing, talking, or even touching the mouth and nose and then a surface. Those who were to test positive on an antibody test would still have to be careful not to transmit the virus from surfaces due to poor hygiene.
Looking ahead to the eventual development of a vaccine, the relative stability of the coronavirus could be crucial. If this is accurate, the scientists at John Hopkins say it would mean that, once a vaccine is developed, there would only be a single vaccine rather than a new one being required every year.
Despite this potentially good news, there is still a second crucial unknown – we don’t know how the virus will behave across the year.
Research on other human coronaviruses and respiratory diseases suggests that they tend to peak in the winter months but struggle in the hot and humid weather of the summer. But this cannot be taken for granted. Some epidemiologists have warned that warmer weather might not be enough to make a significant dent in the transmission of the virus.