Vaccines are some of the most effective preventative measures against the spread of disease. After a person receives a shot, their immune system mounts a response against the contents of the vaccine (typically a dead or weakened virus) and creates antibody-producing cells that “remember'' how to destroy the virus if the body is infected again. A vaccine for the coronavirus has the potential to prevent countless people from falling ill with Covid-19. Vaccine development can take several years, but the pandemic has forced scientists to develop and test vaccines as fast as they safely can. In early December, Pfizer and BioNTech’s vaccine was authorized for use in the United States, just 11 months after its conception.

Most vaccines use a weakened or dead version of the virus they fight against, but Pzfier's vaccine takes a different approach. The vaccine uses messenger RNA (mRNA) to prompt the body’s cells to create a synthetic version of the virus’ spike protein. After the cell creates the protein, it discards the mRNA. The immune system, detecting the spike protein, responds by creating protective antibodies. These antibodies protect the vaccinated person against getting infected if they are exposed to the real virus. The use of mRNA is newer than many other approaches (no other mRNA vaccines have yet been approved by the FDA), but the technology is thought to be more quickly and economically manufactured than other vaccines. mRNA vaccines are still held to the same safety and effectiveness standards as other vaccines and have to complete multiple clinical trial phases before they are approved. A final analysis of the Phase 3 trial of Pfizer’s vaccine showed that it was 95% effective in preventing infection. In those that do get infected, the Pfizer vaccine has also been shown to decrease the risk of serious illness.

Distribution of the vaccine will be a challenging process. Questions about who gets the vaccine, where they get it when they should get it, and how it’s transported there need to be answered. Currently, Pfizer is attempting to make 50 million doses by the end of 2020 and 1.3 billion doses in 2021. Multiple countries have secured a portion of the doses and will likely distribute them to their population in varying ways. The distribution of the vaccine will need to consider what groups in the population are at the highest risk and need the most protection against Covid-19. Healthcare and essential workers, the elderly, and those with underlying conditions are all either more likely to be exposed to the virus or to experience more serious symptoms. In the United States, healthcare personnel and residents of long-term care facilities will be offered the vaccine first. The next challenge is how to get vaccines to those populations. In order to successfully transport the vaccines, Pfizer will need to collaborate with a variety of companies, federal and state agencies, and health workers. On top of the massive coordination necessary to transport them, there is the added challenge of keeping the vaccines at the correct temperature. The mRNA used in the vaccine is fragile and encased in lipid nanoparticles. To stop the mRNA molecules from falling apart, the vaccine must be frozen at a temperature of -94° F (-70° C), which is significantly colder than most standard freezers. Dry ice can be used to achieve a cold enough temperature, however, replenishing the ice will take extra manpower. Pfizer’s vaccine also requires two doses, given approximately three weeks apart, for full immunity to be achieved. Two doses double the supplies, work from those administering the vaccine, and transportation needed to protect a population against Covid-19. Some people may not come back for the second dosage after the first one, leaving them at a higher risk of infection. Altogether, moving the vaccine from production into the hands of the people that will administer it will be an enormous undertaking.

The Pfizer vaccine was first authorized for use by the United Kingdom. In October, the country began a “rolling review” of the vaccine, in which regulators received and reviewed the data as it came in. The vaccine was authorized on December 2nd. Less than a week later, the U.K. began distributing the vaccine on a leveled basis in an attempt to vaccinate those who are at the highest risk first. The country has arranged for the purchase of 40 million doses of the vaccine, which would allow them to vaccinate approximately 30% of their population. After the United Kingdom approved the vaccine, Bahrain also announced its approval and promised that the vaccine will be provided for free to its citizens. This is the second vaccine the country has authorized, as Bahrain has also approved China’s Sinopharm vaccine. On December 8th, Canada became the third country to authorize the use of the Pfizer vaccine. Canada began vaccinating its citizens this week. By the end of the month, 249,000 doses of the vaccine are expected to be shipped to the country. The United States FDA authorized the vaccine for emergency use for individuals 16 years of age or older two days after its northern neighbor. 100 million doses of the vaccine are committed to the United States, or enough to vaccinate approximately 15% of the population. Saudi Arabia, Kuwait, and Mexico have also approved the vaccine.

While Pfizer is the first company with a vaccine that received approval in the United States, there are many other companies still working to develop, test, and gain approval for their own vaccines. Moderna has also produced an mRNA vaccine that touts similar efficacy to the Pfizer vaccine. The company announced that it was applying to the FDA for authorization on November 30th. AstraZeneca and the University of Oxford have developed an adenovirus-based vaccine. Their clinical trials have surprisingly found that half the dosage was 90% effective (two full dosage shots was 62% effective) after accidentally giving the decreased dosage to volunteers. Many more companies are in the process of completing their Phase 3 trials including Johnson & Johnson, Novavax, and CanSino.