As COVID-19 continues its spread around the world, scientists and public health officials are trying all kinds of solutions to slow and eventually end the pandemic.

One of those solutions is a vaccine. The introductions of vaccines are what have stopped the spread of major diseases from polio to measles to whopping cough in the past. You’ve likely received a few of them in the form of a poke at different trips to the doctor’s office when you were younger.

But it’s a long and tedious journey from the outbreak of a disease to that simple poke. That’s why it could be a long time before one is widely available for coronavirus, making it all the more important for everyone to follow the recommendations of the CDC so we can slow the spread of this killer.

Making a vaccine requires several steps:

Identifying the disease and finding an antigen

This part goes on in labs, without any testing on humans yet. Scientists try to figure out ways to attack the virus. This looks different depending on the virus and the vaccine. In vaccines like the ones for chicken pox and measles, people get infected with just enough of a live disease to build up an immunity that prevents viruses from reproducing over and over.

In other vaccines, like polio and rabies, an antigen completely inactivates, or effectively kills, the virus. Then there’s vaccines for diseases like Hepatitis B, which only uses a part of the virus or bacteria, but enough in there that the harmful virus can no longer replicate. Depending on the type of disease, this can be the longest or most difficult step, and the one that can be the toughest to receive funding for if officials believe there will never be a viable cure.

Phase I Trials

Next up, the vaccine gets tested in healthy adults, and scientists have to make larger quantities of the vaccine to make sure it's possible.

Phase II Trials

During these, way more people get tested, scientists figure out dosage amounts and they compare those people to others who didn’t get the vaccine at all. Companies also work at ways they’re going to make, package and distribute the product.

Phase III Trials

Now that they know a drug is safe on healthy people, here’s where the intense testing starts on people who will actually need a drug or vaccine. This stage requires thousands of testers, and then years of reviewing the data after seeing the results come in. If this goes well, the vaccine can then start to be distributed.

The length of these processes can depend on the type of disease, but it’s not unusual for development to take 10, 15 or 20 years. It’s also not unusual for some solutions to never make it pass step one. It’s incredibly difficult to find the antibodies that can take down a disease, and even if scientists think they’ve found it, they might not receive the funding to continue their research if it’s a disease that doesn’t affect many people.

It’s also not uncommon for a vaccine to make it past the first step, drum up a lot of excitement, but then realize in the bigger tests that it’s just not doing as well as everyone had hoped. All in all, scientists can work for years on a potential cure, only to see it never materialize.

Probably. In an incredibly swift and generous move, Chinese scientists shared the sequenced genetic material of the virus back in January, allowing several scientists and drug makers around the world to start coming up with different vaccines, as well as drugs that could help to alleviate symptoms. Some are based off vaccines that were in the works for different respiratory diseases like SARS and MERS in the past, which is part of the reason that many teams have been able to develop solutions so quickly.

And since it’s a pandemic, officials are doing everything they can to speed up the trial times. But even working quickly, the competition to find a cure is becoming what the New York Times is calling a “global arms race.” Even if smart people come up with a vaccine that’s deemed safe and effective, creating enough and getting it out to the potentially billions of people around the world who will need it will come with incredible supply chain, regulatory and political challenges.

That’s why it’s important to hope that the various vaccine trials go well, but not to rely on that as the end to this pandemic. Instead, focus on social distancing or self-quarantining, hand washing and listening to the CDC recommendations for keeping you and your neighbors safe during an unprecedented time.