Governments are starting to lift lockdowns, and some are considering immunity passports, where all constraints are lifted for those earlier infected.
What’s the problem?
A critical unanswered question on the COVID-19 pandemic is whether or not those tested positive can contract it again?
The battle against COVID-19(1) could be made far simpler if those infected develop an adequate immunity level through the development of antibodies. Conversely, if re positive cases are confirmed, the battle to end the disease will be difficult.
Answering the questions on re-catching could hold the key to regaining individual freedoms for those who have developed antibodies, to the lifting up of economies and, long term could lead to societies attaining “herd immunity.”
But are you immune from COVID-19 if you’ve already been infected?
Few infections never recur once you’ve had them, such as smallpox and measles. But you can get many others again, such as tetanus and influenza.
Studies suggest that at least a proportion of patients who have had COVID-19 will be shielded from another infection – at least initially. But the science is far from sure. Here’s what we know so far.
First, a quick recap about antibodies
When we are affected by an infection for the first time, our body needs to respond rapidly to the threat. So within hours, it activates our inherent immune system. This system is fast-acting but isn’t targeted to a particular risk.
The inherent immune system’s attack distracts the infection while the body produces a more specific but slower response against the virus through the adaptive immune system.
The adaptive immune system releases antibodies to fight the infection. They are measured in the blood when trying to confirm who has been infected with SARS-CoV-2, the virus that is responsible for COVID-19.
The body produces various types of antibodies to respond to different components of the virus. But only a few can block the virus from entering cells. These are called “neutralizing antibodies.”
Why do some people test positive again?
There are reports from different nations of people hospitalized with COVID-19 who tested negative when they were discharged before testing positive again.
However, research from China found those who retested positive didn’t get any ill. This observation indicates that these patients were sporadically shedding the virus and were at the fag end of their initial sickness, rather than infected again with COVID-19.
The throat and nasal swab tests used to detect the virus also can’t confirm whether the corona is alive or not; therefore, they could have just been shedding lifeless virus. This could clarify why their close contacts didn’t test positive or become sick.
[Also Read: Why Covid-19 is so hard to control?]
Do other coronaviruses generate immunity?
The other four types of human coronaviruses (HCoVs) – NL63, 229E, HKU1, and OC43, – cause about fifteen to thirty percent of the common colds globally. Two of these—HKU1 and OC43 —are a subgroup of coronaviruses known as beta coronaviruses, as are MERS, SARS-CoV, and SARS-CoV-2.
A research from 1990 found infection with human coronavirus 229E generated protective immunity from that specific virus. But one year later, as antibody levels depleted, these people could be infected again. The scientists hypothesized a cyclic infection pattern, with people getting coronavirus infections every 2 to 3 years.
When scientists examined 128 samples from patients who had recovered from SARS (SARS-CoV or severe acute respiratory syndrome), they found 90% had strong neutralizing antibodies. In contrast, 50% had positive T cell responses, inferring they were likely to be immune.
Given this data about other coronaviruses, infection with SARS-CoV-2 may offer some immunity from getting infected for a second time. But the duration of that immunity and whether everyone becomes immune are unclear.
Do other coronaviruses provide cross-immunity against COVID-19?
Cross-immunity is where immunity against one infection gives protection from another infection.
In one study, scientists tracked newborns up to twenty months of age. They confirmed that infection with human coronavirus OC43 generated neutralizing antibodies that may have shielded against HKU1. In simple words, it provided cross-immunity.
If there is cross-immunity between HCoV-HKU1 and HCoV-OC43, which are both beta coronaviruses, they could likely generate cross-immunity with SARS-CoV-2.
But unfortunately, the current tests for COVID-19 (blood tests and throat and nasal swabs,) can’t provide us clarity about cross-immunity.
Why could cross-immunity be crucial?
Cross-immunity with the other two beta coronaviruses can notably explain some of the contradictions we see with COVID-19.
For instance, why do some people under 60 years of age experience extreme and even fatal illness with COVID-19, while others over 90 years old completely recover?
Given that immunity to these two other beta coronaviruses is prevalent and possibly fluctuates over time, patients with COVID-19 may have had different antibody levels against HCoV-HKU1 and HCoV-OC43 when they got infected with SARS-CoV-2. This could have contributed to varying levels of the extremity of COVID-19 infection.
It’s even likely that cross-immunity could have been detrimental rather than safeguarding because it might lead to an over-active immune response. This phenomenon can be noticed in dengue, another viral infection.
The problem of immunity to COVID-19 will be resolved over time. But for now, researchers are still piecing the information together.
How can you protect yourself and others?
Advice on how to avoid spreading and contracting the virus differs from country to country – as some are easing restrictions and lifting lockdowns, others are still in the pandemic’s tight grip.
As questions remain over the danger of reinfection, it is suggestible to adhere to social regulations and restrictions, even if they have recovered from the infection.
[Also Read: How to Help Others During Coronavirus Quarantine]
The thumb rule is still to maintain social distancing whether or not you’re positive. And that’s because, at this juncture, we are not sure. If someone continues to discard the virus, if those viral particles are still alive, you can still infect them. So the basic rule is always to maintain social distancing.