Have all the headlines on infection numbers and antibody testing left you feeling confused? If so, you’re not alone. Even researchers have been scratching their heads, uncertain of how this pandemic is going to play out. But antibody testing is looking really promising. So let's look at how it works and how they hope to use it.
Research on immune responses to coronaviruses has shown they can be tricky. Studies on SARS has suggested infection may trigger long-term antibodies, but that peak immunity also seems to start dropping within a few months. Studies on other coronaviruses, such as those responsible for many cases of the common cold, have shown our immunity against these types of infections could be far more complicated, making the development of a vaccine difficult if not impossible.
The virus that causes SARS (SARS-CoV) and the virus that causes COVID-19 (SARS-Cov-2) are extremely similar, let’s call them close cousins. They’re both betacoronaviruses, and both have the ability to cause sudden and acute respiratory disease. Some scientists believe research into their other similarities could shed light on treatment and prevention options.
Previous studies on SARS immunity has shown infection can leave people with virus-specific antibodies for around 2 to 3 years. However (and this is a big however), most people see a drop in antibodies long before that, with a peak generally averaging between 2 and 4 months after infection. And past vaccine research on SARS has proven coronaviruses present one pitfall after the next when it comes to finding any reliable way of forcing lasting immunity.
Research into other coronaviruses is even bleaker. A study on coronavirus 229E and OC43, two of the viruses responsible for the common cold, shows immunity peaks within weeks of infection. Tests show some immune cells can persist for about a year, but just enough to create asymptomatic infection when the virus is reintroduced.
This is both good news and bad news. Asymptomatic infection means the person isn’t showing any physical signs of illness, but they are still shedding the virus. In other words, they aren’t suffering or at risk of complications, which is great, but they’re also well enough to be spreading the infection without realizing it. If SARS-CoV-2 runs a similar course, with some reinfected people shedding the virus but showing no symptoms, then we could see a resurgence simply due to the number of unaware super-spreaders.
The immune system is made up of many different types of cells, some that identify invaders, some that attack those invaders and others that keep a working memory of everything the body’s had to fight off. A recent Scientific American article explains that having antibodies in your system specific to a virus isn’t the same as having the types of antibodies you need to prevent reinfection. You need an army of specific fighters like T cells for that, and those particular types of cells seem to drop off pretty quickly in the case of coronavirus infections.
There’s a good possibility that our immune systems simply don’t have the capability to protect us against COVID-19 and similar infections in the long term. And in some cases, any lasting immune response could even be dangerous. There’s some evidence that suggests cross-infection with other coronavirus strains, and maybe even previous infections with COVID-19, could trigger deadly immune responses in response to SARS-CoV-2 exposure in some people.
Obviously, this could lead to serious pitfalls when it comes to attempts at developing a safe and effective vaccine for COVID-19.
Scientists have been using SARS vaccine research as a springboard for COVID-19 studies. Some are specifically looking for proteins that appear constant in all the mutations of the strains, something that won’t mutate out and render a vaccine ineffective as quickly as researchers can develop a target against it.
One big concern is potential unintended effects that can come with targeting specific proteins. The Infectious Diseases Society of America (IDSA) has seen previous issues where vaccine targets cause unexpected autoimmune responses in otherwise healthy people. Given the issues we’ve already seen in COVID-19 patients, safe vaccine development against this disease could be next to impossible. It’s really too early to say whether researchers will be able to overcome these obstacles.
Don't be disheartened, research on COVID-19 is still just beginning, so hopefully, good news is out there, waiting to be discovered. It’s important to be cautious, though. If curing coronaviruses was simple, we’d have found a cure to the common cold a long time ago. There’s still so much we don’t know about this disease, and until we understand exactly what’s going on, all we can do is continue trying to flatten the curve and keep exposure rates as low as possible. Mask up, everybody, this is looking like it's going to be a long ride.
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