To the Editor

Keehner et al.¹ (Sept. 30 situation) report a resurgence of SARS-CoV-2 bacterial infections, primarily with the delta variant, in vaccinated well being treatment personnel in San Diego in July. The reduction in vaccine protection was allegedly due to emergence of the delta variant, waning immunity, and the conclusion of masking requirements in California.

Desk 1. Desk 1. SARS-CoV-2 Infection in Vaccinated HCWs at Fondazione IRCCS Policlinico San Matteo, Pavia, Italy (February–August, 2021).

In Could 2021, vaccine defense towards equally symptomatic and asymptomatic an infection was 83% amongst 3720 vaccinated health treatment personnel at Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.² We did not notice a subsequent maximize, but instead a reduce, in the frequency of breakthrough infections (Table 1). The delta variant appeared in Italy³ in April and subsequently grew to become predominant. In line with details from England,⁴ our conclusions exhibit a persistent vaccine effectiveness versus the delta variant. While the stages of vaccine-elicited neutralizing antibodies were being diminished in opposition to the delta variant, the result of these antibodies was not abolished.⁵ The discrepancy involving our data and the data from California may well reside in the persistence of an indoor masking requirement, wide inhabitants screening, and superior vaccination protection in Italy by August 31 (71% protection with a person dose and 61% protection with two doses), all of which minimize the circulation of the virus.

Daniele Lilleri, M.D.
Carlo Marena, M.D.
Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
[email protected]

Fausto Baldanti, M.D.
Università degi Studi di Pavia, Pavia, Italy

This letter was revealed on December 15, 2021, at NEJM.org.