The only way to determine if protective immunity from COVID-19 lasts a lifetime or just a few short months is to monitor WA’s 500 ‘recovered’ cases for as long as the virus continues to circulate in the community, according to UWA novel viruses expert Associate Professor Allison Imrie.
“When people recover from the infection – when their immune response has successfully controlled replication of the virus and the infectious virus has been cleared from their body – antibodies produced against the virus are detected by antibody tests performed on blood samples,” she said.
“But we don’t yet know if these antibodies are protective, that is, whether a person who has recovered from COVID-19 and tests antibody positive, is protected from a second infection.”
As we move along the road to recovery, it is crucial that WA keeps up its guard and the entire community remains supportive of intensive public health initiatives keeping a lid on the COVID-19 virus, warns Dr Imrie, a virologist from the UWA School of Biomedical Sciences.
Lessons from past pandemics about 'second waves' – including the 1918 Spanish Flu – were crucial, as these outbreaks had eventually been successfully controlled with the same classical public health approaches in use now – such as improved hygiene and distancing to curb person-to-person transmission.
“In 1918 with the Spanish Flu, you see these curves where transmission declined and then people became fed up with being kept inside and they started to go out and also public health officials said ‘Yes, transmission has declined, we can start to move about a bit more’,” said Dr Imrie.
“Once people started to become more used to being out again and cases started to increase – because they were mingling more – they actually did not want to listen to the instructions to go back home. They said, ‘Oh no, I don’t think so’ and they continued to go out and that was directly linked to the increase in cases and more deaths – the second wave.”
And a more recent key lesson from the SARS (SARS-CoV) pandemic in 2002-2003 was that it had been effectively controlled in only eight months without a vaccine. This was due to human-to-human transmission being interrupted by continual community-wide support for intensive public health measures including surveillance, prompt isolation of patients, strict enforcement of quarantine of all contacts and community quarantine in some areas.
The current COVID-19 pandemic had been “almost predictable” said Dr Imrie, with virologists well aware that the more we “disrupt nature” the more likely we were going to be exposed to a new emerging disease that was highly virulent and could spread around the world.
“We have known for quite some time that if we go out and change the environment – if we go out and cut through jungle and so on – we are exposing ourselves to ecosystems that we were not exposed to previously and that there are new viruses everywhere, certainly bacteria and parasites as well,” she said.
“The COVID-19 virus – known as SARS-CoV-2 – is a scary virus but it certainly could be worse. These viruses are out there, they are in nature, in bats and likely in other animals too. It is quite possible that this new COVID-19 virus was already circulating before the cases were identified associated with the wet market in Wuhan in December 2019. The wet markets may have just been an event that amplified what had already been occurring.
“There are strong feelings about these wet markets, the way the animals are trafficked and packed together very tightly in cages. This makes them very stressed, they then produce a lot of faeces and this then mixes with blood and it is a very easy way for humans to get exposed to viruses that infect animals.
“Now there will certainly be a lot of work done to try to track where the COVID-19 virus might be in other animals and for how long back the virus might have been circulating for.”
When the current pandemic had eased, Dr Imrie said it was vital that adequate continuous funding was assured for both animal monitoring for emerging diseases and fast-response emergency public health services, so we did not find ourselves having to play catch up.
“There is an American program called PREDICT that is funded by the National Institutes of Health and the researchers go out into various environments and they sample animals, sequence those microbes in those animals and they look at the links between what is escalating out there in animals and what can emerge into humans. So this work is going on all the time, as long as they are funded to do it,” she said.
“You have to fund these structures and these intuitions so that they can respond much more quickly and have people who are trained and ready when needed. But in non-pandemic times, it is easy for governments to allocate the funds somewhere else, where it is considered it is needed more. So then when something like COVID-19 happens, you are playing catch up again.”
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