July 23, 2021

Delta variant poses a global threat despite increased production of vaccines

Weekly COVID Vaccine Research Update

Friday, July 23, 2021

Original post can be found on the Duke Global Health Innovation Center's Launch and Scale Speedometer website.


High-income country confirmed dose total: 6.3 billion
Upper-middle-income country total: 2.4 billion
Lower-middle-income country total: 3.1 billion
Low-income country total: 331 million
COVAX total: 3.2 billion
Total worldwide confirmed purchases of Covid-19 vaccines: 14 billion doses


Delta variant poses a global threat despite increased production of vaccines. 

Author: Joslin Coggan

While businesses return to full capacity and mask mandates are lifted in much of the US and several other countries with relatively high vaccination rates, there is growing concern about the impact from the rapidly spreading COVID-19 delta variant. The delta variant was identified in India in December 2020 and was the dominant variant during the country’s devastating outbreak in the spring of 2021. At the beginning of June 2021, the delta variant had spread to 62 countries. The World Health Organization reports the delta variant has now spread to 124 countries driving a surge of COVID-19 cases.

Countries with high access to vaccines are seeing a rapid spread of the delta variant due to factors including increased transmissibility compared to other variants, relaxed restrictions, and stalling rates of vaccination. Parts of the US are experiencing a fourth wave driven by the delta variant despite the fact that all individuals 12 and over are eligible to receive the vaccine. Rates of additional vaccination have started to drop substantially in the US. According to the CDC, 56.3% of the total population have received at least one dose and 48.8% of the total population is fully vaccinated, which is far short of the numbers required to curb the pandemic. In the US, rates of new cases are increasing most rapidly in regions which have the lowest rates of vaccinations, including many of the southern states. Mississippi, Alabama, and Arkansas are among the states with the lowest vaccination rates in the country and are seeing increases in cases. Only 33.9% of the population in Mississippi is fully vaccinated and the state is seeing a rise in hospitalizations. In the past three weeks, the state has seen over a 200% increase in hospitalization of COVID-19 patients.

The delta variant spreads 50% faster in unvaccinated individuals than the earlier known alpha variant. Young people, many of whom are still unvaccinated, are increasingly spreading the delta variant in Europe. For example, the Catalonia region of Spain has experienced a sharp increase in cases over the past few weeks, which health officials in part attribute to the end of school and large gatherings of young people. The region has re-imposed curfews and capacity restrictions in towns where cases are rapidly rising.

Vaccine Effectiveness against the Delta Variant 

The increased rates of infection in places with enough supply of vaccine such as the US could have been prevented through higher rates of vaccinations. The authorized vaccines currently used in the US and Europe can reduce the spread of the delta variant and significantly decrease the risk of severe symptoms. A recent study published by the New England Journal of Medicine found that there was only a mild difference in vaccine effectiveness of two doses of the Pfizer and AstraZeneca vaccines with the delta variant compared to the alpha variant. However, the study found a more substantial difference between the effectiveness against the variants among individuals who only received one dose of the vaccines. One dose of Pfizer was found to be 30.7% effective against the delta variant which is notably less than the 48.7% one dose effectiveness against the alpha variant. Some individuals only receive the first dose of two dose vaccines based on the belief that immunity is already sufficient or fear of side effects. In order to slow the spread of the delta variant, it is important that both doses of two dose vaccines are administered.

The delta variant poses the greatest threat to countries around the world with very low levels of vaccination. Less than 2% of the population in all of Africa have been fully vaccinated, which leaves the region at a great risk for rapid surges of the virus. Already, the delta variant has started to take hold in Africa and accounts for 95% of the cases sequenced in South Africa. Last week, the continent experienced a 43% week-on-week increase in COVID-19 related deaths. The greatest burden of deaths was reported in Namibia, South Africa, Tunisia, Uganda and Zambia.  The increase of the delta variant in Africa poses a huge threat, and it may be too late to prevent the full effects of the new wave. In many countries, the public health measures that kept COVID-19 at bay for over a year are no longer working as well due to the higher transmissibility of the delta variant. Most low- and middle-income countries do not have the health systems capacity to deal with large surges, and we are likely to see collapse of health systems as happened in India, and is happening now in IndonesiaUganda, and other countries facing a rapid increase in hospitalizations.

Addressing the Delta Variant 

Vaccines have proven effective against the delta variant, but the majority of the world still does not have access to vaccines. We need to even more urgently prioritize exporting and delivering vaccines to countries with low vaccination rates before health systems are overwhelmed and death rates soar.

Recent weeks have shown that countries with higher vaccination rates are also not in the clear.  Hospitalization rates are increasing in much of the US and Europe, and health systems are once again feeling the strain of increased cases.

To counter the new variant, vaccine hesitancy needs to be addressed and individuals must be encouraged to receive full doses of the vaccines.

Finally, large outbreaks of the delta variant increase the risk of mutation and emergence of even deadlier variants. Vaccines may not be effective at combating future variants if the virus is left unchecked in many regions, which would leave the world back at square one.


Significant updates, news, and trends we saw last week:

For more information on our research on Covid-19 vaccine supply, please see https://launchandscalefaster.org/COVID-19