INVESTORS banking on a coronavirus vaccine to save the world economy in 2021 need to temper their expectations as scientists increasingly warn of a long and difficult road ahead.

While drug companies are making progress in the quest to find a cure for a disease that triggered the worst recession since the Great Depression, questions remain about how effective the first wave of vaccines will be, how easy they will be to distribute to more than 7 billion people and then how many will agree to take them.

The future for global growth relies on the answers to those questions as a new wave of the pandemic means health fears and government restrictions continue to inhibit daily life and commerce. Even when a successful immunization system does come along, it won’t be an instant economic panacea, said Chris Chapman, a portfolio manager at Manulife Investment, which manages more than US$660 billion.

“In terms of actually getting back to pre-COVID or trend growth, it could take more than a year,” said Chapman. “The timing of the recovery will be delayed, but there is still expectation of a vaccine at some point next year.”

For decades, the world economy relied on central bankers and finance ministers to pull it out of crisis, on the basis that if you pump the right amount of money into an economy, a recovery will eventually follow.

This time is different, as investors look to scientists and data from vaccine and treatment trials for signs of hope just as much as they pore over stimulus plans coming out of Washington, Beijing or European capitals. The longer the hunt for an effective vaccine lasts, the weaker economic expansions will be.

To be sure, science could yet make major breakthroughs in the near term. If even only a small proportion of the population such as health care workers and the most vulnerable are immunized, that could make a big difference to the resumption of everyday life. Savings built up by households and businesses in 2020 could be unleashed in 2021.

Pfizer Inc. said this month it could seek emergency-use authorization in the United States by late November for its vaccine with German partner BioNTech SE. Moderna, another frontrunner in the race, is also looking at the possibility of an emergency approval this year if it has positive interim results next month.

“There is a fair prospect that by the late spring, vaccines will be available in quantities sufficient to protect the most vulnerable groups,” said Neil Ferguson, an epidemiologist at Imperial College London, and former COVID-19 adviser to the U.K. Government. “But at least until then, life will unfortunately remain a balancing act between reopening society and keeping the virus in check.”

Scientific hiccups may slow things down too. Johnson & Johnson paused clinical trials of its COVID-19 shot this month after a participant fell ill, weeks after AstraZeneca Plc and the University of Oxford stopped studies for the same reason. On Friday, both companies announced plans to resume their U.S. trials.

Effective treatments that would also help the economic recovery are also a mixed picture. Disappointing trial results this month for the much-hailed drug remdesivir from Gilead Sciences Inc. showed the antiviral treatment doesn’t save the lives of COVID-19 patients, despite U.S. President Donald Trump extolling its benefits. Still, U.S. regulators cleared the drug for use last week and Gilead has challenged the recent findings citing other positive results.

While there are hopeful signs from some antibody treatments being tested, the steroid dexamethasone is one of the only other therapeutics showing a meaningful benefit, and is aimed at people with very severe symptoms.

Even if an effective vaccine is discovered, the logistics of distribution will still mean disruption to work, travel and leisure will remain, with only a small subset of the population expected to receive a shot in the first instance anyway.

That all spells trouble for global growth, even as data in the United States and euro area are likely to show this week that it rebounded smartly in the third quarter and didn’t collapse as much as once feared.

(SD-Agencies)