Hospitals in the U.S., the U.K., and Canada have begun distribution of the first vaccines for COVID-19 created for large-scale use. The European Union plans to begin distribution by the end of December, and more vaccines will become available across the world in 2021.

Obviously, this is good news. The vaccine could save untold thousands of lives and could slow the spread of the pandemic that has altered life around the world. The creation of multiple vaccines by companies in many countries in such a short time is surely impressive from a scientific standpoint.

However, it is much too early to celebrate as if the pandemic was over. It isn’t, and it won’t be for quite some time. The distribution of the vaccines may be cause for long-range optimism, but it is not an immediate solution. Distribution will take more months even in the best-case scenario, and there are still many unanswered questions.

In fact, there are some scenarios where news of the vaccines could actually make things worse. If the public becomes complacent and modifies behavior putting everyone at greater risk, then introduction of the vaccines may actually backfire.

So, let’s start with the details and unanswered questions about the vaccines being distributed: The two currently being distributed are those of Pfizer and Moderna. Both vaccines are given in two doses at spaced intervals to provide full and long-lasting immunity.

The United States and wealthy Western countries have signed contracts with all major vaccine providers to gain access to hundreds of millions of doses for themselves. That volume is not currently in existence. By the end of 2020, the U.S. is expected to have access to around 40 million doses, enough to vaccinate 20 million of its people, and mass production of not just the vaccines but also the means to administer vaccination is not a fast or easy process.

The vaccine is being rationed, with first healthcare workers and then elderly people in nursing homes given first access. Dr. Anthony Fauci, the leading immunologist at America’s National Institutes of Health, says vaccines might be available to the general public in the U.S. by May or June of 2021.

Well, coronavirus is currently killing more than 3,000 Americans a day. If this pace continues, about 100,000 Americans are expected to die in January. The vaccines won’t be able to prevent that, because they will only have been distributed to very few Americans by then.

If all works as planned, the vaccines might be able to significantly slow down the spread of the coronavirus in the U.S. next summer. That would be if the vaccines prevent both individuals from developing symptoms or catching the virus and spreading it asymptomatically.

According to findings, the Moderna vaccine has been confirmed to prevent asymptomatic spread, but the Pfizer vaccine has not yet been evaluated in this regard. One problem would be if the vaccine does not prevent people from spreading coronavirus yet gives recipients the false hope that it does.

Another problem is if recipients give up on social distancing and mask wearing after getting vaccinated. The vaccines are reportedly successful at a level of around 90% when administered in two doses, but that still means there is a risk of spreading coronavirus, especially in the initial period after the vaccination shots, when the results might not been fully manifested.

In practice, it is not just people who get vaccinated that might give up on social distancing. Coronavirus deniers, who hated social distancing from the start, will take the vaccine as an excuse to stop wearing masks in public, even though they haven’t been vaccinated.

There might be people who assume that, if other people are vaccinated, they don’t need to take precautions to protect themselves. Given that the rate of vaccination will not begin to approach a majority until the end of 2021, anyone who prematurely gives up on social distancing will be putting themselves and the public at risk.

In America, there is also a significant number of people who oppose vaccination in general. The right-wing media is pushing conspiracy theories to sow distrust about vaccines. Fox News pundit Tucker Carlson, for example, said the coronavirus vaccine was about “social control.” According to a survey by the Kaiser Family Foundation, a health group, 20% or so of Americans say they won’t get vaccinated.

Vaccines will not stop the massive increase in sickness and death that is already taking place this winter. They might slow down the pandemic in summer 2021, but that is not guaranteed either.

Waiting for the vaccines to be developed never was a solution, and it’s not a solution now. The countries that saved the most lives and kept their economies going better than elsewhere have been those that adopted preventative measures from the start with commonsense tactics like mask-wearing and quarantining.

These social distancing tactics must continue for the time being and into 2021. Distributing vaccines and social distancing are complementary, not exclusive, strategies.

In 1918, there was no vaccine for the “Spanish flu.” It died down of its own accord after spreading through the population and mutating. That may still happen by the time the whole world is vaccinated against COVID-19.

Mitchell Blatt is a columnist with China.org.cn.