Lockdowns and social distancing, masks and regular handwashing, expanded coronavirus testing, contact tracing -- all form part of public-health strategies to slow the spread of COVID-19 until one or more vaccines can be created to end the crisis.
The urgency of the crisis has led research regulators around the world -- from the U.S. Food and Drug Administration (FDA) to Russia's federal health and biomedical agencies -- to loosen rules so that necessary human trials can be fast-tracked.
Many governments are also now preparing the groundwork to speed the production and distribution of emergent vaccines that prove to be safe and effective.
The World Health Organization (WHO) says there are now more than 100 possible vaccines in the research pipeline around the world.
Initial clinical tests on small groups of people have begun for nearly a dozen of them.
But experts warn it will still take months or more before human trials can be completed on larger test groups to ensure candidate vaccines are both effective and safe for distribution to hundreds of millions of people.
Rushing Forward In Russia
So some Russian experts are questioning a vaccine timeline suggested last week by Russian Health Minister Mikhail Murashko as being overly optimistic.
Murashko told the State Duma that Russian developers could have a vaccine available around the end of July. He did not specify which developers were leading the research race in Russia or what exactly he meant by "wider application" of a resulting vaccine.
When asked by Russian television about the work by Novosibirsky Vektor, the State Research Center of Virology and Biotechnology, Murashko replied that some Russian developers were "more advanced and closer to the finish line" than others.
"We would very much like to see a number of vaccines entering our market," Murashko said. "A vaccine is a very subtle product that unveils its qualities during applications on a wider population, including during later stages. A given drug is monitored over the course of months and years.
"Preclinical trials are under way already," Murashko said. "Everything is proceeding according to schedule. So far, there have been no glitches. Hence, our prediction is that the first results and access to its wider application will be available around the end of July."
But according to Vitaly Zverev, head of the molecular technologies laboratory at Moscow's Mechnikov Research Institute of Vaccines and Sera, Murashko’s timeline is unrealistic.
"Of course, you can create a prototype vaccine during such a brief period of time," Zverev told Current Time, the Russian-language network led by RFE/RL in cooperation with VOA. "But it is impossible to have it properly tested. Hence, it would be premature to say that a mass vaccination will be launched in July."
Zverev said he hoped Russia refrains from any mass vaccination campaign "until the safety and efficiency" have been proven.
"That's because any vaccine would be applied to completely healthy people and we must be absolutely certain that it is safe," Zverev explained. "This cannot be tested in a few weeks or even months. It is impossible to complete this colossal amount of work in four months. Some things simply cannot be sped up."
Irina Yakutenko, a molecular biologist and science journalist, told Current Time that rushing ahead and distributing an inadequately tested vaccine to millions of Russians would be a giant “backward leap” for science.
Yakutenko warned that such a campaign could put many lives in danger, “negating all the [scientific] standards that enable our well-being.”
Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases (NIAID), has said an aggressive timeline is possible that would beat earlier predictions by having a COVID-19 vaccine ready as early as November.
"We have a good chance -- if all the things fall in the right place -- that we might have a vaccine that would be deployable by the end of the year, by November-December," Fauci told CNN on May 27.
Fauci explained that vaccine trials by NIAID researchers and their private-sector collaborators were now proceeding "at risk" with the four phases of human trials.
That means researchers are trying to shorten the vaccine-development process by taking "the next steps before the results of the previous step" are completed.
Several pharmaceutical and biotech companies are seen as private-sector leaders that have been working with governments and research institutions in the race to create coronavirus vaccines.
Oxford University's world-renowned vaccinology center, the Jenner Institute, selected AstraZeneca as its partner to help develop its adenovirus vaccine -- one of several so-called viral-vector vaccines being developed for COVID-19.
Such vaccines use a virus that is generally harmless but can provoke an immune response.
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The Oxford University-AstraZeneca researchers hope they can include proteins of the coronavirus in an injectable vaccine against the adenovirus -- allowing people to build up immunity to COVID-19 without contracting the disease.
Reports on early clinical trials suggested a vaccine could be ready by September. But AstraZeneca is now downplaying that timeline as overly optimistic. "The hope of many people is that we will have a vaccine, hopefully several, by the end of this year," AstraZeneca head Pascal Soriot said on May 28.
AstraZeneca announced recently that it had secured orders for at least 400 million doses of its still-unproven vaccine along with $1 billion in funding from the U.S. Department of Health and Human Services.
The U.S.-based multinational pharmaceutical corporation Pfizer is working on several possible vaccines -- conducting its first human trials in early May and launching clinical trials with the German firm BioNTech in Europe and the United States.
One of its most promising candidates is a so-called messenger-RNA (mRNA) vaccine.
Albert Bourla, Pfizer's chairman and chief executive officer, has said his company now believes it could have a vaccine available by the end of 2020. "If things go well, and the stars are aligned, we will have enough evidence of safety and efficacy so that we can have a vaccine around the end of October," Bourla said on May 28.
The U.S.-based vaccine-development firm Novavax started human trials of its NVX-CoV2373 vaccine earlier this week in Australia.
Novavax is trying to develop a protein-subunit vaccine for the new coronavirus. The firm has issued positive public statements in recent weeks, bolstering its share price on stock markets.
Reuters reported on May 28 that Novavax was buying a manufacturing facility from the Serum Institute of India in an attempt to be able to produce 1 billion doses of a future vaccine during 2021.
China's CanSino adenovirus vaccine has emerged as the leading candidate among several potential "inactivated vaccines" being developed in China.
But former U.S. FDA Commissioner Scott Gottlieb said last week that the vaccines being developed in the United States appeared to be more promising than those being developed in China.
Gottlieb told CBS-TV’s Face The Nation program on May 24 that data on potential vaccines that are in clinical development in China "didn't look overwhelmingly strong."
"Those [Chinese] vaccines, if they do work, probably are going to provide lower levels of immunity than the platforms that the U.S. and Europeans are working with," Gottlieb said.
"So I think we're going to have a better vaccine, and I think we're probably going to have it sooner, based on where we are in clinical development, some of the early progress that we've shown."
In addition to the Oxford-AstraZeneca research and Pfizer, Gottlieb said the U.S. firm Moderna and the Swiss drugmaker Lonza were also working on "promising" potential coronavirus vaccines.
Moderna began human trials for its mRNA vaccine in early May, fueling hopes among its executives that it could have a vaccine ready by year-end.
In mid-May, the Trump administration suggested that early data from Moderna's clinical trials raised hopes that a few hundred million doses of vaccine could be delivered by the end of 2020.
However, The New York Times concluded that its review of data made available by Moderna did not support the company's optimistic public statements.
Questions have also been raised about moves by Moderna's top executives to dump nearly $30 million worth of company shares after the promising early results were announced.
Last week, Moderna's share price dropped dramatically after U.S. media reports highlighted side effects experienced by a volunteer who took part in a clinical trial, including nausea, chills, and aching muscles.