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Last Updated : Aug 03, 2020 06:00 PM IST | Source: PTI

Macular degeneration may increase severity of COVID-19: Study

Complement, one of the immune system's oldest branches may be influencing the severity of COVID-19 disease, said the researchers at Columbia University in the US.


People with age-related macular degeneration – an eye disorder caused by overactive immune system -- are at greater risk of developing severe complications and dying from COVID-19, according to a study.

Complement, one of the immune system's oldest branches may be influencing the severity of COVID-19 disease, said the researchers at Columbia University in the US.

The findings, published in the journal Nature Medicine, suggest that existing drugs that inhibit the complement system could help treat patients with severe disease.


The researchers also found evidence that clotting activity is linked to COVID-19 severity and that mutations in certain complement and coagulation genes are associated with hospitalisation of COVID patients.

COVID-19 Vaccine

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How does a vaccine work?

A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.

How many types of vaccines are there?

There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.

What does it take to develop a vaccine of this kind?

Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.

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"Together these results provide important insights into the pathophysiology of COVID-19 and paint a picture for the role of complement and coagulation pathways in determining clinical outcomes of patients infected with SARS-CoV-2," said Sagi Shapira, who led the study with Nicholas Tatonetti, both professors at Columbia University.

If complement and coagulation influence severity of COVID-19, people with pre-existing hyperactive complement or coagulation disorders should be more susceptible to the virus, the researchers said.

That led researchers to look at COVID-19 patients with macular degeneration, an eye disease caused by overactive complement, as well as common coagulation disorders like thrombosis and hemorrhage.

Among 11,000 patients who came to Columbia University Irving Medical Center with suspected COVID-19, the researchers found that over 25 percent of those with age-related macular degeneration died, compared to the average mortality rate of 8.5 percent, and roughly 20 percent required intubation.

The greater mortality and intubation rates could not be explained by differences in the age or sex of the patients, the researchers said.

"Complement is also more active in obesity and diabetes and may help explain, at least in part, why people with those conditions also have a greater mortality risk from COVID-19," Shapira said.

People with a history of coagulation disorders also were at increased risk of dying from COVID-19 infection, the researchers added.

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First Published on Aug 3, 2020 05:55 pm