By Arild Drivdal*
Vaccines prepare and train the human immune system to recognize and fight infections by producing antibodies against known diseases. Traditional vaccines consist of either live or inactive pathogens that teach the body how to respond to a “real” infection. In the case of Covid-19, there are more than a hundred so-called candidate vaccines in different stages of development, with some already in clinical trials. A vaccine has been approved in Russia, but it is considered experimental because it did not go through the required three steps of clinical trials and is seen, at least in part, more as a propaganda effort than as a real vaccine. According to Bill Gates, who is dedicating all his time to helping find a Covid-19 vaccine, there are 8-10 strong candidate vaccines that may prove to be effective, and if they are, some of these may become available in a few pioneer countries within the next 12 months.
Production. Developing a vaccine is however only the first step in the process of immunizing the world population, which is an especially difficult task when so many people will need the vaccine. Other steps in the chain include production, distribution, financing and use, each of which comes with its own set of challenges. In the case of Covid-19, production is mostly related to logistical factors, such as having enough production capacity in pharmaceutical factories, which depends both on setting up safe production processes and preparing production facilities. It may take 12-18 months for them to get organized, but we can assume that public and private entities will be able to meet the production challenge.
Distribution. Distribution will depend mostly on whether the vaccine requires a cold chain, that is, whether it needs to be kept refrigerated, whether it can be taken orally and whether health systems can handle the demand. Large-scale immunization usually happens through intensive campaigns (or during antenatal and early childhood medical visits), but a Covid-19 campaign is likely to be the largest vaccination campaign ever organized on the planet and there might not be enough health systems capacity to manage it effectively. The polio vaccine was introduced in 1961, but for a variety of reasons, wild polio was eradicated in Africa only a few weeks ago, almost 60 years later, and the disease has still not been eradicated globally. During the Ebola outbreak in West Africa, there was in fact a vaccine that proved to be effective, but it took a whole year after the outbreak started before it became widely available and even after that, there have been several other Ebola outbreaks on the continent.
Equitable access. In many cases, vaccines are not available because they are not profitable enough for the pharmaceutical companies that produce them, and in other cases they may be too expensive for poor countries to afford. Many African countries have seen children die because they could not afford measles vaccines or cover the cost of getting them to the population. The equitable distribution of vaccines is a huge issue that has not yet reached the public consciousness but will hit poor countries like a fist to the face if and when a Covid-19 vaccine becomes available. In the way the global vaccine system is set up, it is a near 100 percent probability that rich countries will receive a Covid-19 vaccine first and perhaps years before poor countries. Some governments have made it a point to tell their electorate that they will prioritize their own populations, and some people may argue that governments that pay for the development of the vaccine should be able to access it first. This is how the “market mechanism” typically works, but there is some hope that the global nature of the Covid-19 pandemic will encourage equitable distribution of a vaccine. A main factor in this access and pricing dynamic is the need for pharmaceutical companies to protect their profit margins in the United States, where drug prices are much higher than in the rest of the world. If a drug or a vaccine is sold at a low cost in Africa, it will be difficult for these companies to justify a higher price in the North American market where they generate most of their profits. Past experience has shown that the profit imperative of pharmaceutical companies can be a very powerful shaper of the availability and cost of vaccines.
Psychology. For a vaccine against infectious diseases like measles or Covid-19 to be effective, it is necessary to immunize at least 50 percent of the population, usually more, to achieve herd immunity, the level where the virus cannot find enough new hosts to infect. In recent years, anti-vaccination movements have grown in many countries, often fed by conspiracy theories and pseudo-science circulated in social media. In other countries, such as in the case of the polio vaccine, cultural and religious beliefs have stopped parents from immunizing their children. In the DRC, many people rejected the Ebola vaccine because they believed it was part of a political conspiracy against them. The risk of large numbers of people refusing a Covid-19 vaccine should not be underestimated, especially if some of the early vaccines prove unsafe or ineffective.
Taken together, the uncertainties along every step of the vaccine supply chain tell us that we cannot depend on a “vaccine solution” to the pandemic. We will need to adapt to a situation where neither vaccine nor treatment will be available for several years, leaving us to focus on prevention and mitigation measures instead. In this process, it is important to have a rational and sound understanding of the known facts; adjust protective measures to the situation the country faces at any given time; and find the right balance between public health and economic needs.
*Arild Drivdal possui um Mestrado em Saúde Pública (MPH) pela Universidade de Harvard e é treinado em epidemiologia e saúde comunitária.