Otago Daily Times

Light at the end of Covid tunnel with mRNA vaccines

- Gwynne Dyer is an independen­t London journalist.

ALL the usual caveats apply: don’t go out and celebrate, don’t let your guard down, it’s still going to be a long haul. This northern winter would be ‘‘hard’’, warned Ugur Sahin, cofounder and chief executive of BioNTech, the German company that announced the first effective Covid19 vaccine only a week ago. It couldn’t be rolled out fast enough to reduce infections much in the current wave, he said.

The publicatio­n on Monday of positive results for a second vaccine, this time by the US company Moderna, strengthen­ed the optimism. Clearly, this coronaviru­s can be beaten, and there are nine more potential Covid vaccines already in thirdstage (final) human trials.

But again, the riders: there will be at least half a million more Covid deaths this winter — or more than a million if people don’t observe the lockdowns and other restrictio­ns meant to contain the spread of the virus. ‘‘What is absolutely essential,’’ Sahin said, ‘‘is that we get a high vaccinatio­n rate before autumnwint­er next year.’’ That’s when it could really be over.

And yet there is cause to celebrate, because of the 11 vaccine candidates that were already in thirdstage trials, both the frontrunne­rs are ‘‘messenger ribonuclei­c acid’’ (mRNA) vaccines, an entirely new approach that allows a much faster response to novel viral infections.

Traditiona­lly, new vaccines took around 10 years to be developed, tested and approved for general use. For the new mRNA vaccines, it has been 10 months.

After Chinese scientists posted the full genetic sequence of the Covid19 virus online on January 10, ‘‘we were making RNA within a week or so’’, Drew Weissman of the University of Pennsylvan­ia said. Weissman then supplied that RNA to both BioNTechPf­izer (Pfizer is a large American company that gives the German innovators US distributi­on and regulatory clout) and Moderna.

RNA carries the genetic instructio­ns from the nucleus of the cell to build whatever protein is needed, and for the past decade researcher­s have been trying to fabricate ‘‘messenger’’ RNA that could be inserted into human cells. The mRNA would then use the cells’ own genetic machinery to make vaccines and other medically useful proteins.

By 2018 several companies had cracked the problem of getting the mRNA past the body’s immune defences. With the full RNA sequence of the new coronaviru­s in their possession, all they had to do was choose which bit of the coronaviru­s RNA to use in the vaccine.

Obviously not the whole thing, or it would rebuild the entire virus in the cell. Just a harmless segment of the virus’ RNA, copied millions of times by the vaccinated person’s cells, would alert the body’s immune system and train it to destroy any invading virus with that sequence. (They chose the ‘‘spike’’ the virus uses to attach itself to the human cell.)

Several companies had mRNA vaccines ready for testing within two or three months, and the results have been spectacula­r. BioNTech/Pfizer has just reported 95% efficacy for its vaccine, and last weekend Moderna reported 94.5%.

Even better, both BioNTechPf­izer and Moderna included all major ethnic groups and a significan­t number of elderly people in their thirdphase trials. All categories responded well to the vaccines (which is not always the case with other vaccines).

Yet another mRNA vaccine in thirdphase trials could be even better, because it will be far cheaper than the BioNTechPf­izer vaccine ($US39 ($NZ56)for two shots) or the Moderna jab ($US74 for two shots), if it pans out. At Imperial College in London, Robin Shattock’s team is working on a ‘‘selfamplif­ying RNA’’ vaccine that may require as little as 1⁄100 1% the amount of vaccine.

The mRNA technique may mean that future pandemics can be dealt with far more quickly. The vehicle is already available and waiting to carry the next vaccine. Just ‘‘plug and play’’ for any future coronaviru­s, as one researcher put it. (We have had three new coronaviru­ses in the past two decades.)

Pfizer boss Albert Boura went even further: ‘‘It’s the greatest medical advance in the past 100 years.’’ Well, maybe, though a vote taken today would probably plump for antibiotic­s instead. But we are only beginning to see the potential of mRNA.

There are already trials under way for a wide variety of other illnesses: not just safer, more effective influenza, polio and HIV vaccines, but immunother­apies for cancer, heart conditions, cystic fibrosis and other systemic and congenital diseases.

There is a long, dark winter still ahead of us, no doubt, but miracles may await us over the horizon. And we can now be sure that the light at the end of this particular tunnel is not an oncoming train.

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