GLEAM Model Urges International Cooperation for Vaccination Efforts



News about vaccines to protect against COVID-19 has overtaken our feeds since early December. Margaret Keenan, an elderly woman in the UK, received the first coronavirus vaccine in the world on December 8, 2020. The U.S. administered its own first dose on December 14, 2020.


As healthcare workers and high-risk and elderly individuals are prioritized for vaccine distribution in parts of North America, the European Union, China, Russia, Israel, and similarly wealthy countries, many are waiting and wondering when it will be their turn. Across 56 countries, 63 million doses were administered as of mid-January, of which one-third have been administered in the U.S.


Meanwhile, numerous lower-income countries have not even begun vaccination efforts. Global inequity in health care and access is laid bare and especially glaring today. This urgent problem not only disadvantages vulnerable populations but it also undermines the global strife for pandemic containment. International cooperation is more important than ever, and scientists leading the GLEAM Project offer evidence from a large-scale computation model to emphasize the significant consequences of cooperative and uncooperative vaccine allocation strategies for global rates of mortality.


A recent paper led by researchers at Northeastern University uses the Global Epidemic and Mobility Model (GLEAM) to study the spread of COVID-19 in space and time. It is the same model that was used to study the effectiveness of global travel restrictions earlier in 2020. Their model assumes that the pandemic follows the trajectory that “was initially observed in 2020,” and it takes into account the various pandemic-related interventions put in place by various countries. It also assumes that distribution of a single-dose vaccine begins on March 16, 2020 and that 3 billion total doses are administered in the following 6-month period at a pace of 125 million vaccines per week.


The researchers consider two sets of scenarios: 1) a vaccine that is 80% effective vs. one that is 65% effective, and 2) a global cooperative allocation scenario vs. one that is uncooperative. If countries cooperate, the first 2 billion vaccine doses are distributed equitably in proportion to each country’s population. If the countries refuse equitable cooperation, the first 2 billion doses only reach a specified set of 47 advantaged countries including the U.S., Canada, China, Russia, and several European countries.


The model simulation leads to two main figures: 1) the median number of deaths in each scenario and 2) the proportion of deaths averted in comparison to a baseline scenario in which there is no vaccine distribution.


The results are striking. According to the model, a vaccine that is 80% effective would avert 33% of deaths if the global distribution effort is uncooperative. If countries commit to cooperation, however, the proportion of deaths averted almost doubles to 61%. For a vaccine that is 65% effective, uncooperative global distribution would avert 30% of deaths while a cooperative strategy would increase this percentage to 57%, which is very close to the proportion of deaths averted with an 80% effective vaccine.


Further, if wealthier countries are prioritized for vaccine administration in the uncooperative scenario, they are able to achieve a modest gain in the proportion of deaths averted. On the other hand, disadvantaged countries unsurprisingly can protect fewer people in the uncooperative scenario. For example, with an 80% effective vaccine, Western Europe would achieve death aversion at 74% with uncooperative global distribution but 55% with a cooperative strategy. Northern American numbers are similarly 67% and 53%. Countries in Western Africa, however, would achieve a flipped 13% death aversion with an uncooperative strategy but an impressive 93% death aversion proportion with a cooperative, equitable global vaccine distribution strategy. Similarly, the South-Eastern Asian proportions of death aversion for uncooperative and cooperative strategies are 5% and 62% respectively.


The authors acknowledge that their model has limitations but nonetheless affirm that it provides compelling and informative “general information concerning the statistical effectiveness of the different vaccine allocation strategies.” This work was made public in September 2020, yet much has changed since. Alongside the hopeful yet unsatisfactory pace of global vaccine distribution, new variants have emerged and crossed borders. Most recently, 100 cases of the so-called “South African variant” have been identified since December, and vaccine producers are testing to affirm the efficacy of vaccines against these new challenges. But the undeniable backdrop to all of this is that, as it stands, global vaccine distribution efforts do not meet the ideal of equitable cooperation. High-income countries such as those considered in the GLEAM model simulation, which make up 16% of the world’s population, have consumed over 60% of the vaccine supply.


Leaders and experts in healthcare are urging national leaders to correct the status quo, a “catastrophic moral failure” in the words of the WHO Director-General Tedros Adhanom Ghebreyesus. The GLEAM model shows us the dire consequences of non-cooperation and what we stand to gain from coming together. Global citizens worldwide can only hope that cooperation is what nations choose.