Lower prevalence of congenital cytomegalovirus infection in Portugal: possible impact of COVID-19 lockdown?

Cytomegalovirus (CMV) is the most frequent cause of congenital infection all over the world. Its prevalence ranges from 0.2 to 2.2%. Transmission from children to their pregnant mothers is a well-known risk factor, particularly if they attend a childcare centre. This study aims to compare the prevalence of CMV congenital infection (CMV_CI) in Portugal (Lisbon) between two studies, performed respectively in 2019 and 2020. In the 2019 study, performed in two hospitals, we found a 0.67% CMV_CI prevalence, using a pool strategy previously tested with saliva samples. In the 2020 study, using the same pool approach in four hospitals (the previous and two additional), and based on 1277 samples, the prevalence was 0.078%.Conclusion: The close temporal coincidence with COVID-19 lockdown suggests that these measures may have had a significant impact on this reduction, although other explanations cannot be ruled-out. What is Known: • Cytomegalovirus is the leading cause of congenital infection. • Behavioural measures decrease cytomegalovirus seroconversion in pregnant women. What is New: • From 2019 to 2020 there was a significant reduction in the prevalence of congenital CMV infection.

Saliva pools for screening of human cytomegalovirus using real-time PCR.

Human cytomegalovirus (HCMV) is the leading congenital infection agent in the world. The importance of screening this infection has been debated, as 10-15% of the asymptomatic newborns with HCMV at birth will present late sequelae. The aim of this study was to test the feasibility of using saliva pools from newborns in a screening program for congenital HCMV infection, in two Portuguese hospitals. The screening was based on the use of pools of 10 saliva samples for detection of viral DNA by real-time PCR. Whenever there was a positive pool, the samples were tested individually, and for each positive sample the result was confirmed with a urine sample collected in the first 2 weeks of life. The study involved 1492 newborns. One hundred and fifty pools were screened, with 14 positive results in saliva, but only 10 were confirmed in urine samples, giving a prevalence of congenital HCMV infection in both hospitals of 0.67% (CI95% 0.36 to 1.23%).Conclusion: The overall prevalence of congenital HCMV infection in both hospitals was 0.67%. The use of saliva pools proved to be effective for the screening of this congenital infection, allowing timely screening and confirmation in a large population, with associated cost reduction. What is Known: • Newborn screening for HCMV is desirable. • Saliva is a good and practical sample. What is New: • The feasibility of using saliva pools for a large-scale screening. • The cost reduction of this strategy.

Pooling Saliva Sample as an Effective Strategy for the Systematic CMV Screening of Newborns-A Multicentric Prospective Study.

BACKGROUND: Cytomegalovirus is the most common cause of congenital infections worldwide. Screening all newborns in the first 2 weeks of life is the only way to detect all cases of congenital infection, allowing the monitoring of children with asymptomatic infection at birth and early intervention. AIM: In this multicenter study, we aimed to evaluate the feasibility of using a saliva pool strategy for mass screening in 7 Portuguese hospitals, and to estimate the current prevalence of this congenital infection in these hospitals. METHODS: A total of 7033 newborns were screened between June 2020 and June 2022, and 704 pools of 10 saliva samples were analyzed by polymerase chain reaction (PCR). RESULTS: Of the 704 pools analyzed, 685 were negative and 19 had positive PCR results for cytomegalovirus. After individual PCR testing, 26 newborns had positive saliva results, of which 15 were confirmed by urine testing. Thus, this study's prevalence of congenital infection was 0.21% (95% confidence interval: 0.12%-0.35%). CONCLUSIONS: In this study, the pooling strategy proved to be effective for the systematic screening of newborns, although this low prevalence raises questions regarding the cost-effectiveness of implementing universal screening. However, this prevalence is probably the result of the control measures taken during the pandemic; therefore, the rates are expected to return to prepandemic values, but only a new study after the pandemic will be able to confirm this.

Evaluation of saliva pools method for detection of congenital human cytomegalovirus infection.

Human cytomegalovirus (HCMV) is the most frequent cause of congenital infection, leading to long-term sequelae especially sensorineural hearing loss (SNHL). Since 5-15 % of the asymptomatic newborns will develop late sequelae, the implementation of a universal screening would allow the identification of infected children and early intervention. The aim of this study was to validate the use of saliva pools of 10 and 20 samples for the detection of HCMV congenital infection. Four spiking samples (negative saliva matrix added with known concentration of AD169 strain culture supernatant) and a set of 12 saliva samples, collected from newborns with confirmed congenital infection in their first three weeks of life, were tested individually and after dilution in 10 and 20 pools by an "in-house" RT-PCR. Both pool methodologies, 10-pool and 20-pool samples, had 100 % sensitivity and specificity when compared with individual samples. This methodology could allow a cost reduction close to 85 % and 89 %, respectively for the 10-pool and 20-pool approach, when compared with testing each sample individually. This significant reduction may open the possibility to perform the newborn screening for HCMV in a large-scale.