More Good News on the Delta Variant Virus


If your local newspaper is anything like mine, you’re probably inundated with scary news about the new Delta variant of the Covid-19 virus. It is true that new infection cases are rising, but they are almost entirely among those who are unvaccinated. A recent post (Vaccines and the Delta Variant) was meant to reassure my readers who are already vaccinated. Today, I have more good news to share.

Two public health researchers, Leslie Bienen of the Oregon Health and Science University – Portland State University School of Public Health and Monica Gandhi, infectious disease physician and professor of medicine at the University of California, San Francisco, share this news in The Wall Street Journal. They say a new study from the U.K. found that the vaccines are still incredibly effective in preventing serious illness, even with the Delta variant. The Pfizer vaccine was 96% effective after two doses in preventing hospitalization, which means the unvaccinated are more than 25 times as likely to be hospitalized with Covid as those who are vaccinated.

This is probably an understatement since the vaccinated cohort was older and had a higher incidence of pre-existing conditions than the unvaccinated one. The Johnson & Johnson vaccine produces strong neutralizing antibodies and cellular responses against the Delta variant, still present eight months after administration. The Moderna vaccine was not used in this study, but may have similar results as Pfizer since they are both mRNA developed vaccines.

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) both have asserted their confidence in the vaccines. They also jointly announced that no boosters are necessary at this time.

There is also much talk about the Delta variant making people sicker. There is actually no evidence to support this claim. The authors reviewed publicly available data from the CDC and compared hospitalizations per case, particularly in regions where a new variant is more common. They found that the hospitalization data support none of the alarming headlines suggesting Delta is more dangerous than earlier strains.

Further analysis of hospitalization data tells us whether healthcare systems are overwhelmed, and helps us predict deaths with high reliability. Positivity data are less reliable, especially the relationship between infection and hospitalizations becomes weaker in highly vaccinated countries like the U.S. The authors conducted similar analyses in April, when headlines were raging that the U.K. variant, now called Alpha, was driving surges in kids. They found that it wasn’t, and that juvenile hospitalizations weren’t rising in places with a high prevalence of the Alpha variant.

The authors say, “Whatever else we know or don’t know about Delta, its prevalence clearly isn’t driving hospitalizations. When we look at current hospitalization data across the country, the most striking predictive pattern is that a high vaccination rate in a region accurately predicts a lower hospitalization rate.”

The hardest question to answer is transmissibility, because it isn’t possible to conduct controlled trials comparing how many people get infected with a particular variant. New variants may be more infectious, as some suspect the Delta variant is, or they may only be better at reproducing themselves in an infected person’s body. For whatever reasons, the Delta variant is becoming the dominant strain in the U.S.

Unfortunately, politics continues to influence headlines and even public health policy. The latest concerns the infection rates and hospitalizations in Florida being announced in the headlines, not by the CDC or even the Florida public health officials, but by the White House. Is it possible they fear the rising popularity of Governor Ron DeSantis?

One comment

  1. Good information about vaccine protection. The political comment at the end was unnecessary and inflammatory

    Comment by Martha on July 31, 2021 at 10:03 am