COVID, MASKS, VACCINES AND CHILDREN - A STUDY.

High frequency of SARS-CoV-2 infection in children admitted to academic hospitals in central South Africa 

O P Khaliq, MMedSc, PhD ; S C Brown, MMed (Paeds), PhD ; B Pitso,MB ChB, MMed (Paeds) ; N E Tabane, MB ChB, MMed (Paeds) Department of Paediatrics and Child Health, School of Clinical Medicine, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa Corresponding author: O Khaliq (khaliqop@ufs.ac.za)

The COVID‑19 pandemic affected the globe from 2020 to 2023, following its discovery in December 2019 in Wuhan, China.[1] Globally, >2.6 million cases and 17 000 deaths were reported from 17 April 2023 to 14 May 2023.[2] The virus has mutated rapidly since its discovery, resulting in different variants worldwide.[3] However, vaccinations for COVID‑19 were manufactured to protect individuals from severe complications after infection.[4] 

The safety of these vaccines in children was unknown. Therefore, children under the age of 12 years were not vaccinated in South Africa (SA) until July 2023. 

SA has had four variants since the emergence of COVID‑19, and this study focused on the fourth variant, Omicron.[3] The Omicron variant was first discovered in SA and Botswana in November 2021.[5] This variant was reported to spread more rapidly than previous variants.[6] 

Interestingly, infections were noted even in environments where COVID‑19 safety protocols, such as wearing of masks, were observed.[7] The Omicron variant was also reported to have high asymptomatic carriage, with mild disease patterns, making it difficult to detect and control.[8] 

During the emergence of the Omicron variant, the virus spread rapidly in adults and children, with higher admission numbers noted in paediatric wards in Germany.[9] Another increase of paediatric admissions was noted in the USA.[10] In Romania, paediatric cases also increased in children (≥10%).[11] Countries such as China, Korea, Japan and SA experienced increased paediatric admissions during the time of the Omicron variant.[12-15] 

The Omicron variant is involved with lower antibody neutralisation and lower vaccine effectiveness, resulting in risk of re-infection.[6] Moreover, antibody neutralisation is higher in children with mild infections than in adults with mild infections, and even higher in children ≤10 years of age than older children. [16] 

Cloete et  al. [5] hypothesised that increased paediatric admissions were attributed to decreased frequency of mask use in children, and lower vaccination rates, as children ≤12 years were not vaccinated at the time of their study.[15] 

Children wore masks less frequently than adults because it was believed that they had a lower expression level of angiotensinconverting enzyme II (ACE2) and transmembrane protease serine  2 (TMPRSS2) (binding sites for the SARS-CoV-2 virus) than adults.[17-19] The low expression of ACE2 receptors is suspected to result in mild symptoms in children. At the same time, other findings suggest that this could be due to children having fewer or no underlying conditions.[20,21] 

The immune response in children and adults is also reported to differ. Chou et al. [22] have shown that children have stronger interferon (IFN) responses to SARS-CoV-2 and more T-cells than adults. The stronger IFN response to infection results in a lower cytokine storm, leading to mild infection.[21] 

Furthermore, cytokine levels in children with mild COVID‑19 were similar to those of healthy children, indicating that children only have a mild inflammatory response during infection.[23] Children with mild COVID‑19 infections are usually asymptomatic, and where not, have shorter hospitalisation stays than those with severe COVID‑19 disease.[24] 

Wearing masks and performing COVID‑19 screening before admission was no longer a standard procedure during 2022. At this point, children were not yet vaccinated in SA. This study aimed to investigate the prevalence of COVID‑19 infection in children aged 0 - 1

Discussion 

This study aimed to investigate the prevalence of SARS-CoV-2 infection in unvaccinated children during the Omicron variant (fourth wave). Results show that just under half of the children included in the study had both IgM and IgG antibodies present, indicating current or recent active infection. However, they were admitted for other conditions. All positive cases found in the study were incidental, as none of these children were tested for SARSCoV-2 upon admission, or admitted due to infection. 

and the lowest infection rates were observed in children between 61  -  144 months. These results differ from a multicentre observational study conducted in SA in the Tshwane district that investigated clinical profiles of all children infected with SARS-CoV-2 (6  287 children ≤19 years of age) during the fourth wave (Omicron variant). Of the infected children, The highest infection rates were noted in neonates <1  month (60%), followed by infants aged 1 -  12 months and toddlers, aged 13  -  60 months, 14% were aged 0 - 4 years, 20% were aged 5 - 9 years, 32% were aged 10 - 14 years, and 34% were aged 15 - 19 years.[15] 

The infection rates increased with age while in our study, the rates decreased with age. 

Furthermore, of the three COVID‑19 waves, the highest rates of infection were noted in the fourth wave (Omicron).[22] According to the Centers for Disease Control and Prevention update on COVID‑19 in children and adolescents ≤18 years, 11.8% of children were infected during the fourth wave of COVID‑19 in January 2022 in SA.[25] Furthermore, a paediatric registry in the USA

 reported that 24% of children aged between 5 and 11 years tested positive for SARS-CoV-2.[16] The infection rate of the neonates in the current study is also high compared with a study published in Iran, which had an infection rate of 6.1% in neonates.[26] A study in the UK reported that the incidence of SARS-CoV-2 was 5.6 per 10  000 live births. Of these neonates, 42% had severe SARS-CoV-2 infection.[27] Our results may have had a higher infection rate in neonates because the majority of the study population comprised neonates (51.6%). 

The presence of SARSCoV-2 antibodies in circulation determined infection. The presence of both antibodies represents a recent infection, as research shows that the IgM antibody is detected 4  days following infection and reaches its peak on the 20th day, after which it drops.  

Children included in the study were admitted for reasons other than suspected SARS-CoV-2 infection, and none were tested before admission; therefore, their infection status was unknown upon admission. 

In December 2021, the paediatric population of hospital admissions due to SARS-CoV-2 infection was ~18% (462/2  550) in the Tshwane district.[15] Of these admissions, the most common conditions associated with positive antibodies were seizures (20%), acute gastroenteritis (20%), respiratory infections (14%) and bronchopneumonia (15%). The current study’s admission diagnoses differed among the different age groups. In these, the reasons for admission were prematurity (28%), GIT conditions (12.6%), respiratory conditions (12%) and CNS conditions (10%). However, whether the admission diagnoses were due to SARS-CoV-2 infection in these children is unknown, as this study was only focused on infection rates. This study adds new knowledge because most SA studies underreport neonatal data.[1,2] Another study recruited 97 SARS-CoV-2-positive children admitted to a hospital in India.[30] Some of the children were admitted due to COVID‑19, while others were admitted for other reasons but tested positive for SARS-CoV-2 upon admission. The study population was aged 1 - 18 years. The total sample size of the study was lower (n=97) than the current study (n=320). The study found that 30.93% of the children were asymptomatic, while 68.04% were symptomatic. These results differ from the current study as all 46.8% (n=150/320) SARS-CoV-2 infected children were asymptomatic, indicating mild disease. Studies show that pregnant women infected with SARS-CoV-2 are at a higher risk of preterm deliveries.[31-34] 

Another multicentre study conducted in Saudi Arabia described the clinical outcomes of mothers infected with SARS-CoV-2 and their neonatal outcomes. The authors found that out of 204 neonates, 15.5% (n=31) were born prematurely.[35] In the current study, 32.2% of the SARSCoV-2-infected babies were premature. These babies may have been infected via vertical transmission before birth, or the infection may have been acquired in hospital. There are different ways in which vertical transmission can occur, leading to preterm birth.[36] 

SARS-CoV-2 is transmitted through faecal contamination of the birth canal, which can infect the neonate during labour. Vertical transmission via the ACE2 receptors found in the placenta can also affect gaseous exchange and lead to other complications, such as intrauterine death and perinatal asphyxia.[35] However, the likelihood of transmission to the fetus is minimal due to the presence of the placental barrier.[37] Some researchers state that vertical transmission to the fetus might be possible through other receptors (dipeptidyl peptidase-4 inhibitor (DDP4) and cluster of differentiation (CD147) and proteases (Furin).[38,39] In a study by Allotey et al.,[32] the rate of preterm births in women infected with COVID‑19 was 17%, which is lower than in the current study. 

Furthermore, in the current study, mothers were not tested for SARS-CoV-2; therefore, their SARS-CoV-2 status was unknown. However, their maternal COVID‑19 vaccination history was collected, and 61.8% of the mothers with premature deliveries were vaccinated. The rates of COVID‑19-vaccinated adults in the Tshwane district were lower than in this study (32%).[15] 

Our results align with reports published by the SA National Department of Health, which found that 65 -  80% of the adult population had a positive result due to a previous infection or COVID‑19 vaccination.[40] 

A study conducted in Israel from April 2020 to March 2021 revealed that antenatal vaccination with the Pfizer vaccine demonstrated elevated IgG titers, and these antibodies were transferred to the fetus through the placenta.[41] Maternal transfer of anti-SARS-CoV-2 antibodies was found in neonatal circulation 2 weeks after the first dose, indicating neonatal immunity during pregnancy. 

Equally, another study showed that the transfer of SARS-CoV-2 IgG and IgM was possible via breastmilk. 

Notably, both antibodies in neonatal circulation may indicate neonatal immunity more than an active infection.[18] However, in the current study, information on breastfeeding was not collected to confirm this finding. According to Beharier et  al.,[41] it is difficult to confirm whether antibodies found in neonates following delivery may be due to the placental transfer of a seropositive mother or to immune response following the COVID‑19 vaccine. The study reported no significant difference between maternal and neonatal antibody titers in vaccinated mothers compared with previously infected mothers who had recently recovered.

Conclusion 

A substantial number of hospitalised children were infected with SARS-CoV-2. 

All infected children did not have COVID‑19-specific symptoms and were admitted for conditions entirely unrelated to COVID‑19. This may be due to the Omicron variant, which is highly infectious, less virulent and associated with mild disease. 

Noting the high infection rates in the study, vaccination of all children for COVID‑19 is recommended, as vaccinating parents alone does not protect the children from infection.  

As mild as the Omicron infection might have been in children, these kids still ended up BEING ADMITTED. Outcomes good, but parental stress and costs should be taken into consideration.

NO ANTIVACCINE SENTIMENTS WERE EXPRESSED BY THE AUTHORS OF THIS ARTICLE.