- - There was recently a drastic surge in new COVID-19 cases, primarily driven by the Delta SARS-CoV-2 variant, across nearly all states in the United States in the past few days.
- - COVID-19 vaccine breakthrough infections are inevitable due to several reasons, such as i) the Delta SARS-CoV-2 variant poses a higher risk than any currently circulating SARS-CoV-2 variants in terms of increased transmissibility; ii) COVID-19 vaccine breakthrough infections will be likely to frequently occur among the vaccinated vulnerable population, such as immunocompromised individuals and nursing home residents; iii) the greater the percentage of individuals getting vaccinated in the total population, the higher the absolute number of breakthrough infection cases within this population.
- - Evidence suggests that current major vaccines against COVID-19, such as the Pfizer-BioNTech, Moderna, and AstraZeneca vaccines, are still be protective to individuals, especially against severe diseases caused by the Delta variant (e.g., hospitalization, death), despite a potential decrease in the effectiveness against symptomatic infections.
- - People fully vaccinated with COVID-19 vaccines had a much lower risk of getting infected with SARS-CoV-2 (8-fold reduction), progressing to severe diseases such as hospitalization (25-fold reduction) and death (25-fold reduction) compared to those not vaccinated.
“This is becoming a pandemic of the unvaccinated.
We are seeing outbreaks of cases in parts of the country that have low vaccination rates because unvaccinated people are at risk.”
-- Dr. Rochelle Walensky --
Director of the United States Centers for Disease Control and Prevention (US CDC, Source)
There was recently a drastic surge in new COVID-19 cases across nearly all states in the United States (US) in the past few days. Data from the World Health Organization (WHO) showed that over 1.26 million new COVID-19 cases occurred in the Americas between July 18 and July 25, 2021, a 30% increase compared to the percentage from the previous week between July 10 and July 17 (Table 1). The highest number of new COVID-19 cases was reported from the US, which was 500,332 cases and has increased by over 130% compared to the percentage of the previous week (Table 1).
In the following week between July 26 to August 1, the number of new COVID-19 cases reported was similar to the number from the previous week in the Americas, accounting for around 30% of new global COVID-19 cases (Table 1). Again, the US reported the highest number of new COVID-19 cases with over 543,000 cases and a 9% increase from the previous week (Table 1).
Table 1: Newly reported COVID-19 cases between July 18 and August 1, 2021 (Data adapted from WHO, 2021a and 2021b)
New cases between July 18 and 25
Changes in new cases compared to previous week (July 10 to 17)
New cases between July 26 and August 1
Changes in new cases compared to previous week (July 18 to 25)
The surge in COVID-19 cases is especially severe in states such as Florida, which has become, according to The NBC News, the “new epicenter of COVID cases.” As of August 3, 2021, the 7-day daily average number of new COVID-19 cases in Florida was over 15,000 (The New York Times). Furthermore, Florida also broke its previous record for the number of current hospitalizations due to COVID-19, which was set about 1 year ago in July 2020. Over 11,800 patients have been hospitalized as of August 3, 2021, according to the data provided by the US Department of Health and Human Services (HHS).
The new surge in COVID-19 cases was primarily driven by the Delta SARS-CoV-2 variant (the B.1.617.2 lineage). According to the latest data released by the CDC, the Delta variant has replaced the Alpha variant (B.1.1.7) and become the dominant strain circulating in the US, which accounted for at least 83% of the COVID-19 cases in the US (CDC).
We have previously published 2 OE Originals addressing the potential threats of the Delta variant. We feel it necessary to publish on this topic again because of the recent surge in the COVID-19 cases in the US, especially in Florida, to raise our awareness and cautions about the misinformation surrounding the Delta dominant pandemic. In this OE Original, we emphasize two key points based on scientific evidence and evidence only.
Past OE Originals on the Delta SARS-CoV-2 variant*
* Evidence regarding COVID-19 emerges rapidly. These OE Originals can only reflect the best available evidence at the time of publication.
1. COVID-19 vaccine breakthrough infections are inevitable
but should not compromise our confidence in COVID-19 vaccines
“Fewer than one quarter of unvaccinated adults [in the US] think the available [COVID-19] vaccines are ‘extremely’ or ‘very effective’ at preventing death, serious illness, infection, or transmission, and at least one-third say the vaccines are ‘not too effective’ or ‘not at all effective’ at preventing each of these.”
Kaiser Family Foundation COVID-19 Vaccine Monitor: July 2021, Source)
The CDC defines a breakthrough infection as “
An increase in COVID-19 vaccine breakthrough infections should be expected due to several reasons. First, no vaccines can guarantee 100% protection. Second, the Delta SARS-CoV-2 variant may pose a higher risk than any currently circulating SARS-CoV-2 variants in terms of increased transmissibility and vaccine breakthrough infections (Farinholt et al., 2021).
Third, COVID-19 vaccine breakthrough infections will likely frequently occur among the vaccinated individuals who belong to the vulnerable population, such as immunocompromised individuals (Chodick et al., 2021; Tenforde et al., 2021) and nursing home residents (preliminary data reported by CDC).
The fourth reason for the breakthrough infection increase, which is perhaps the most confusing reason, is the increase in population-level vaccination coverage. In other words, the greater the percentage of individuals getting vaccinated in the total population, the higher the absolute number of breakthrough infection cases within this population.
However, an increase in breakthrough infection cases does NOT mean COVID-19 vaccines are no longer effective. On the contrary, evidence still suggests that current COVID-19 vaccines remain effective.
As presented in our previous OE Original published July 19, 2021, current major vaccines against COVID-19, such as the Pfizer-BioNTech, Moderna, and AstraZeneca vaccines, can still be protective to individuals, especially against severe diseases caused by the Delta variant (e.g., hospitalization, death), despite there might be a decrease in the effectiveness against symptomatic infections (For detailed data, please see: Delta and Lambda SARS-CoV-2 Variants: Current Evidence).
For example, the data, which was released by Public Health England and analyzed 14,019 symptomatic cases with the Delta variant, showed that the effectiveness of either the Pfizer-BioNTech vaccine or the AstraZeneca vaccine against hospitalization due to the Delta variant was 94% [95% confidence interval (CI): 85% to 98%], even higher than that against hospitalization due to the Alpha variant (also known as the B.1.1.7 variant, vaccine effectiveness: 92%, 95% CI: 78% to 97%) (Stowe et al., 2021)
2. SARS-CoV-2 infections are occurring in both unvaccinated
and vaccinated groups, but to a much lesser extent in the fully vaccinated population
“... We have 100 million people in this country [United States] who are eligible to be vaccinated who are not getting vaccinated. We are seeing an outbreak of the unvaccinated …
… But the issue is, if you’re going to be part of the transmission chain to someone else, it’s not only impacting you. And you’ve got to think about it, that you are a member of society. You have a responsibility.”
--- Dr. Anthony Fauci ---
ABC News “This week", Source)
Generally, the CDC considers a person fully vaccinated if 2 weeks have passed since the second dose in a 2-dose series or 2 weeks after a single dose COVID-19 vaccine.
A model showed that the SARS-CoV-2 transmission among residents in long-term care facilities (LTCFs) would decrease by about 90% (90% CI: 76% to 93%), compared to that expected given transmission in the community, if over 70% of LTCF residents are fully vaccinated (De Salazar et al., 2021). Moreover, 74% (90% CI: 58% to 81%) of COVID-19-related mortality and 75% (90% CI: 36% to 86%) would also be prevented (De Salazar et al., 2021).
People fully vaccinated with COVID-19 vaccines had a much lower risk of getting infected with SARS-CoV-2, compared to those not vaccinated (8-fold reduction, 21.4 vs. 178.6 weekly COVID-19 incidence per 100,000) based on data released from the White House COVID-19 Press Briefing on August 2, 2021. The risk reduction between the vaccinated and unvaccinated populations was even greater in the incidence of hospitalization (25-fold reduction, 0.1 vs. 2.52 per 100,000) and death (25-fold reduction, 0.04 vs. 0.96 per 100,000) due to COVID-19 (The White House COVID-19 Press Briefing).
In Florida, about 95% of people hospitalized due to COVID-19 were unvaccinated according to the president and chief executive officer of the Florida Hospital Association (The Guardian). In Texas, about 99.5% of COVID-19 mortality occurred in unvaccinated individuals; in Tennessee, about 98% of COVID-19-related deaths and 97% of hospitalizations happened in people who have not been vaccinated (The White House COVID-19 Press Briefing).
An Indian study assessed the clinical outcomes of COVID-19 vaccine breakthrough cases (over 90% of COVID-19 cases in the sample were due to the Delta variant) who had been vaccinated with either the AstraZeneca vaccine or the COVAXIN vaccine (an inactivated whole virus vaccine) (Jagadeesh Kumar et al., 2021). Overall, the study found that both vaccines were effective against Delta-related severe disease and mortality among hospitalized patients who had breakthrough infections.
Specifically, Jagadeesh Kumar et al. (2021) found that the disease severity (3.2% vs. 7.2%; P = 0.0039) and the need for ventilatory support (2.8% vs. 5.9%; P = 0.0154) due to the Delta variant were significantly lower in the vaccinated group compared to those in the unvaccinated individuals. Moreover, COVID-19-related mortality in fully vaccinated people (1.51%, 2/132) was close to 50% lower compared to either that in unvaccinated individuals (3.45%, 23/666) or that in partially vaccinated individuals (3.35%, 9/269) (Jagadeesh Kumar et al., 2021).
"The more infections, the more chance that mutations will occur and thus the more likely selection will enrich the best mutations to improve the virus. Vaccination is the best weapon in the fight to curb transmission.”
--- Dr. Vaughn Cooper ---
Board Director of ASM’s (American Society for Microbiology) Council on Microbial Sciences, Source)
We examined evidence regarding the COVID-19 vaccine breakthrough infections and the protective effects of COVID-19 vaccines on these breakthrough cases. We found that COVID-19 vaccine breakthrough infections are inevitable. However, currently used COVID-19 vaccines are still effective in the sense that they significantly reduced hospitalization and mortality among vaccinated individuals. Altogether, increasing vaccination coverage against COVID-19 remains the most important public health measure to control the COVID-19 pandemic, including the emerging one predominated by the Delta variant.
Chodick, G., et al. (2021). The Effectiveness of the Two-Dose BNT162b2 Vaccine: Analysis of Real-World Data. Clinical Infectious Diseases. doi:10.1093/cid/ciab438
De Salazar, P. M., et al. (2021). High coverage COVID-19 mRNA vaccination rapidly controls SARS-CoV-2 transmission in long-term care facilities. Communications Medicine, 1(1), 16. doi:10.1038/s43856-021-00015-1
Farinholt, T., et al. (2021). Transmission event of SARS-CoV-2 Delta variant reveals multiple vaccine breakthrough infections. medRxiv, 2021.2006.2028.21258780. doi:10.1101/2021.06.28.21258780
Jagadeesh Kumar, V., et al. (2021). Clinical outcomes in vaccinated individuals hospitalized with Delta variant of SARS-CoV-2. medRxiv, 2021.2007.2013.21260417. doi:10.1101/2021.07.13.21260417
Stowe, J., et al. (2021). Effectiveness of COVID-19 vaccines against hospital admission with the Delta (B.1.617.2) variant. Retrieved from https://khub.net/web/phe-national/public-library/-/document_library/v2WsRK3ZlEig/view_file/479607329?_com_liferay_document_library_web_portlet_DLPortlet_INSTANCE_v2WsRK3ZlEig_redirect=https%3A%2F%2Fkhub.net%3A443%2Fweb%2Fphe-national%2Fpublic-library%2F-%2Fdocument_library%2Fv2WsRK3ZlEig%2Fview%2F479607266
Tenforde, M. W., et al. (2021). Effectiveness of SARS-CoV-2 mRNA Vaccines for Preventing Covid-19 Hospitalizations in the United States. medRxiv, 2021.2007.2008.21259776. doi:10.1101/2021.07.08.21259776
WHO. (2021a). WHO weekly epidemiological update on COVID-19 - July 27, 2021. Retrieved from https://www.who.int/publications/m/item/weekly-epidemiological-update-on-covid-19---27-july-2021
WHO. (2021b). WHO weekly epidemiological update on COVID-19 - August 3, 2021. Retrieved from https://www.who.int/publications/m/item/weekly-epidemiological-update-on-covid-19---3-august-2021