As covid-19 cases surge and lockdowns, distancing and mask use continue, the early stages of distribution of two highly effective vaccines — now authorized for emergency use — are a glimpse of light at the end of the tunnel.

But this is just the very beginning of what will be another long journey, in many ways even more complex than the age-old disease control measures that we have all been learning to navigate over the past year.

We have barely begun the real task of coronavirus vaccine rollout. 2021 will be one of the most critical years of our collective lives. Will we be able to slow the swell of cases? Are we prepared for the challenges ahead and ready to manage the inevitable risks?

It is good news that Congress included $28 billion to purchase and deliver vaccines to Americans in the nearly $900 billion stimulus bill, but funding alone will not change the minds and emotions of the public.

The first year of the pandemic was riddled with misinformation and disinformation, and the vaccines will bring more rumors and falsehoods. As hundreds of millions of people around the world get immunized, it’s inevitable that some will experience adverse reactions — and some may still get covid-19. Public health officials need to prepare now for how to answer good-faith questions and fend off deliberate lies.

Even with the two vaccines approved and others in the pipeline, the reality is that we may not have enough for everyone who wants them — or at least not for a while. It will be important to share as much information as possible up front, so the people who want the vaccine will know when and where they can get one. Local communities will want to establish vaccine information centers or online resources where updated information is made available and questions can be answered. It is totally reasonable that people will have questions and concerns about these new vaccines. If officials are dismissive of the concerns or fail to give honest answers about what we know — as well as what we don’t know — then we risk losing public trust not only in the vaccines, but in the system.

Once people do get their first vaccine, the next challenge will be to ensure they come back for the second dose for those vaccines which require it, as both the Pfizer and Moderna products do. For some people, the challenge may not be hesitancy, but more practical concerns: Maybe they can’t take more time off from work to get the second dose, or they didn’t feel well after the first dose. Even the more common but temporary mild headaches and fatigue that trial participants reported could make people hesitate to go back for another dose, leaving them with only partial protection.

Another challenge ahead will be convincing people to continue to wear masks and keep distance even after they are vaccinated. What is the point of vaccinating if you still need to keep wearing mask? Well, for one thing, the vaccine does not work immediately. It takes awhile for the first dose’s protection to kick in, and then you still need to get your second dose to be fully immunized. Even then, in principle, we need to get enough people vaccinated for wider protection before shedding other precautions. But the reality is that while we know that these vaccines can prevent serious disease and death, we won’t yet know whether they prevent transmission to others until enough people get vaccinated.

As additional vaccines wrap up their clinical trials and win approval, new issues will come up. Who decides who gets which vaccines? What will be the criteria? Some of the answers will come down to logistical requirements — the vaccines that need less-extreme refrigeration than the mRNA vaccines Pfizer and Moderna make may be prioritized for poorer countries with less cold-storage capacity. But the differences across the various vaccines, including different numbers of doses needed and varying levels of effectiveness, will need clear and accessible communication starting now, not waiting until there is a confusing mix of vaccines becoming available. We are already in a time of hyper-uncertainty — fertile ground for rumors to evolve and spread. Adding these multiple vaccines without a coherent story as to who gets what and why will only exacerbate the already patchwork landscape of information, leaving the public to create their own interpretation or misinterpretation.

Another potential challenge of having multiple coronavirus vaccines is that individuals may start with one vaccine and want to switch to another, thinking it may have less-severe side effects or be more effective. Careful monitoring of who is taking which vaccines will be especially important for longer term safety monitoring.

With so many people getting vaccinated, there will be adverse events. One type will be coincidental events that seem to be related to the vaccine because they happen around the same time as people get the injection, but that aren’t actually caused by the vaccine. In this case, older populations are being prioritized, along with health-care workers. This is an age group that normally has a higher frequency of illness and death, so sooner or later, someone will get sick or die soon after vaccination. Even if it’s completely unrelated, there’s a danger that people will think it was caused by the vaccine. On the other hand, there may also be adverse events that are actually found to be caused by the vaccine — such as the small number of people who experienced a severe adverse reaction called anaphylaxis following vaccination, due to underlying allergies specific to ingredients in the vaccine. Those with other underlying allergies can still take the vaccine.

Officials will have to look into any such episodes carefully and quickly so that the public can be either reassured that the adverse events were coincidental or alerted to underlying conditions in which the vaccine is not recommended.

We have already seen a proliferation of misinformation and disinformation surrounding the SARS-CoV-2 virus, its origins and the various measures to contain its spread, including vaccination. Some of this misinformation is due to uncertainties, even in the scientific community, surrounding the new virus as well as the treatments and vaccines that are under development or newly approved. People are struggling to make sense of the state of things, relying on news headlines, news releases, heard and socially shared news — and they sometimes wind up spreading misinformation inadvertently.

But there are also those who are purposely spreading harmful, incorrect information, trying to disrupt and seed doubts to undermine public confidence. While fact-checking and debunking rumors is helpful, it is not sustainable. This is a deeper threat, which needs a resilient public armed not only with positive, clear information, but a clear sense of where this is all headed — a path, a direction for a better 2021 within which we situate the story of how society and science can come together around a vaccine that changed the world.

It could be an extraordinary moment. If we get it right.