5 UNKNOWNS IN THE QUEST FOR COVID-19 VACCINE

As the new coronavirus disease (Covid-19) spreads at an alarming rate, experts are ceaselessly questing after a vaccine that can halt the virus stalking the entire globe. According to Nature Research, The Guardian and other reports, the following puzzles will need to be cracked to develop a vaccine

REINFECTION

While there are varying scientific views on this subject, researchers hope that a person infected with the new coronavirus (SARS-CoV-2) develops some immunity against getting reinfected. According to a Reuters report, some discharged patients in China and elsewhere tested positive after recovering, sometimes weeks later. Some of the first cases of “reinfection” have been attributed to testing discrepancies. Others, scientist, say could be because the virus could be active in two phases with dormancy in the middle. A study in China recently showed that two rhesus macaques infected with the virus appeared to be immune when exposed a second time after four weeks. A similar behaviour of the pathogen in the humans could be instrumental in developing a vaccine.

IMMUNITY PERIOD

If humans show signs of developing immunity, it will have to be seen how long it lasts. Immunity against coronavirus types hat cause the common cold doesn’t last long. Even people with high levels of antibodies can still become infected, said Stanley Perlman, a coronavirologist at the University of Iowa. In the case of SARS, data showed antibodies were still present 15 years later. For MERS, the antibodies dropped sharply after recovery. “We don’t have good evidence of long-lasting immunity, but we also don’t have really good data from both SARS and MERS,” Perlman said.

FOCUS AREA

A trial that recently began in the US has been designed to train the immune system to make antibodies that “recognise and block the spike protein that the virus uses to enter human cells”. While it is an attempt the world is pinning its hopes on, “antibody responses to the spike exclusively may not be the whole story,” according to the journal. The vaccine may also need to trigger antibodies that block other proteins of the virus and, possibly, generate cells that can kill the infected cells.

THE TIME FACTOR

According to The Guardian, taking a vaccine candidate all the way to regulatory approval typically takes a decade or more. US President Donald Trump’s remark pressing for a vaccine to be ready by the elections in November stumped many for this very reason. “Like most vaccinologists, I don’t think this vaccine will be ready before 18 months,” the report quotes Annelies Wilder-Smith, professor of emerging infectious diseases at the London School of Hygiene and Tropical Medicine, as saying. This timeline, too, is realistic only if there are no hitches.

EFFECTIVENESS CONUNDRUM

Typically, in the process of developing a successful vaccine, some candidates are found to be either unsafe or ineffective. “Screening out duds is essential, which is why clinical trials can’t be skipped or hurried. Approval can be accelerated if regulators have approved similar products before. The annual flu vaccine, for example, is the product of a well-honed assembly line in which only one or a few modules have to be updated each year,” the report says. Sars-CoV-2, however, is a completely new pathogen in humans and technologies deployed against it are largely untested.