At the moment the majority of the current Covid-19 tests that all the reports are coming from are using PCR. It helps physicians detect the genetic information of the virus, the RNA. That’s only possible if the virus is there and someone is actively infected.

PCR tests are used to directly detect the presence of an antigen, rather than the presence of the body’s immune response, or antibodies. By detecting viral RNA, which will be present in the body before antibodies form or symptoms of the disease are present, the tests can tell whether or not someone has the virus very early on.

PCR gives us a good indication of who is infected. They can be isolated and get in contact with people they’ve been in touch with so they can be quarantined too, just in case. That’s the true advantage of the current major diagnostic tests, you can break that transmission chain and get a clearer picture of what’s happening.

By scaling PCR testing to screen vast swathes of nasopharyngeal swab samples from within a population, public health officials can get a clearer picture of the spread of a disease like Covid-19 within a population. Collection Type: Nasopharyngeal

An antibody test tells us what proportion of the population has been infected. It won’t tell you who is infected, because the antibodies are generated after a week or two, after which time the virus should have been cleared from the system. But it tells you who’s been infected and who should be immune to the virus.

It’s not yet clear how long any immunity period after a Covid-19 infection will turn out to be. Historical studies have indicated that people who survived the 2003 – 2003 sudden acute respiratory syndrome (SARS) outbreak had antibodies in their blood for years after recovery. Both SARS and Covid-19 are caused by coronaviruses, but it’s too early to say if Covid-19 will generate a similar immune response. Reports also indicate that some people have been infected with the virus twice over, meaning these particular patients didn’t develop any immunity at all.

All that said, if public health officials can get a handle on what proportion of the population are theoretically immune to the virus, the information could help lift the social distancing restrictions on movement.

Unlike PCR tests, which commonly use swabs to detect Covid-19, blood samples are usually used for antibody tests. This is because there will be a very small amount of the coronavirus circulating in the blood compared to the respiratory tract, but a significant and measurable antibody presence.

Collection Type: Blood