July 12, 2021 – The Delta variant has rapidly become the dominant strain of the coronavirus in the United States and across the world. A more recent variant, the Lambda, is the source of the infection surge in South America. This variant has yet to be termed a “variant of interest” by public health officials. Furthermore, infection rates are declining across South America.
The following graph provides a snapshot of new infection rates per capita over the past week. Several countries suffer from surging infections: Argentina, Columbia, Cuba, Mongolia, Namibia, the Netherlands, Spain, South Africa, Tunisia, and the United Kingdom. Much of the rest of the world posted relatively low new infection rates.
Despite this snapshot, the trends evoke more significant concern: only South America experienced declining infection rates from the prior week (12% decline in new cases week-over-week). Oceana endured a 73% week-over-week increase; Europe, 30%; North America, 20%; Asia, 17%; and Africa, 12%.
The following graph illustrates this trend in South America: Brazil, Chile, and Peru saw infection rates surge in the spring and early summer. These rates dropped recently as vaccination programs have improved.
More troubling, infection rates are surging in the United Kingdom and threaten to reach levels seen in last winter’s peak. This surge is despite one of the more robust vaccination programs in the world. To a lesser degree, Israel, too, is experiencing increasing cases despite a vigorous vaccination effort.
The United States has posted increasing rates for the past two weeks. Still, this rate remains far lower than observed earlier in the year. Deaths with coronavirus in the United States continue to decline and have reached the lowest point since March 2020.
Studies of these infection surges suggest that:
- Infections are most prevalent in unvaccinated and partially vaccinated persons
- Even with “breakthrough” cases among vaccinated persons, the overwhelming number of cases are mild and do not result in hospitalization or death.
Covid-19 patients occupy a relatively low percentage of inpatient beds (6%, compared to the peak of 42% in January). This census is up week-over-week but remains consistent with where it was three weeks ago.
A curious observation of the preceding chart: sources of the Delta variant (India) and Lambda variant (South America) experienced surging infections following the variants’ introduction. However, in each instance, infection rates later ebbed even before vaccinations reached robust levels.
Infection rates vary widely across the United States, mirroring differences in vaccination rates. Missouri and Arkansas suffered the highest infection rates over the past week, with more than 200 new cases per million people per day. Five other states – Florida, Louisiana, Nevada, Utah, and Wyoming registered rates above 100 per million per day. Conversely, 14 states posted rates of 20 per million per day or lower. Vermont led the way, with only nine new cases per million per day.
Of these seven states with high infection rates, none had vaccinated more than 55% of eligible persons (all required doses, as of June 25). (We selected June 25 in capturing vaccination rates to account for the time needed for immunity to take full effect.) Arkansas (44%) and Missouri (47%) ranked low among all states on vaccination rates, providing fertile ground for the Delta variant to circulate.
At the other end of this spectrum, the 14 states with low infection rates achieved vaccination rates between 60% to 78% of eligible persons. North Dakota was an exception here, with a meager 49% vaccination rate.
From a statistical perspective, we found a significant (each change in vaccination rates of 1% correlated with a reduction of 2.5 new cases per million per day) and significant (p<0.00005) negative correlation between states’ infection and vaccination rates.
We also concluded that low (or high) vaccination rates did not assure high (or low) infection rates. The risk of infection outbreaks increased as vaccination rates lagged. The following graph illustrates the point by showing the range and median new infection rates for quintiles of vaccination rates by state. Note the slight variation in the lowest infection rates for each quintile. However, both the median and highest infection rates increased at each quintile.
The ten states with the highest vaccination rates had the lowest median and top-end infection rates of all five groups. The ten states with the lowest vaccination rates posted the highest median and top-end infection rates.
In summary, the Delta variant has contributed to infection spikes in parts of the United States and globally. High vaccination rates have limited the strength of the surges and the severity of its outcomes. Still, they have yet to deliver community or herd immunity. Further, since few areas have achieved sufficiently high population vaccination, we should anticipate infection outbreaks elsewhere for the foreseeable future. Encouragingly, these outbreaks seem to run their course over time (see India and South America).
The United Kingdom’s experience should be instructive during the next several weeks: at what point will that country’s infections wane, especially given its robust vaccination effort?
Contributing writer:
Mark A. Van Sumeren, strategic advisor, Medical Devices & Integrated Delivery Networks
Health Industry Advisor LLC, provides a regular report on COVID-19 numbers for the health care industry.
For more information, or to sign up for the report, contact Mark at Mark.VanSumeren@HealthIndustryAdvisor.com; or visit www.HealthIndustryAdvisor.com.