Understanding factors associated with protective immunity against emerging viral infections is crucial for global health. Pakistan reported its first COVID-19 case on 26 February 2020, but experienced relatively low COVID-19-related morbidity and mortality between 2020 and 2022. The underlying reasons for this remain unclear, and our research aims to shed light on this crucial issue. We conducted a serial population-based serosurvey over 16 months (rounds 1-4, July 2020 to November 2021) across households in urban (Karachi) and rural (Matiari) Sindh, sampling 1100 households and 3900 individuals. We measured antibodies in sera and tested a subset of respiratory samples for COVID-19 using polymerase chain reaction (PCR) and antigen tests, also measuring haemoglobin (Hb), C-reactive protein (CRP), vitamin D, and zinc in round 1. Participants showed 23% (95% confidence interval (CI) = 21.9-24.5) antibody seroprevalence in round 1, increasing across rounds 2-4 to 29% (95% CI = 27.4-30.6), 49% (95% CI = 47.2-50.9), and 79% (95% CI = 77.4-80.8), respectively. Urban residents had 2.6 times (95% CI = 1.9-3.6) higher odds of seropositivity than rural residents. Seropositivity did not differ between genders. Individuals aged 20-49 years had 7.5 (95% CI = 4.6-12.4) times higher odds of seropositivity compared to children aged 0-4 years. Most participants had no symptoms associated with COVID-19, with no reported mortality. Vitamin D deficiency was linked to seroprevalence. COVID-19 was confirmed in 1.8% of individuals tested via RT-PCR and antigen tests. The data suggests a steady increase in humoral immunity in Pakistan, likely due to increased transmission and associated asymptomatic disease. Overall, this reflects the longitudinal trend of protection against severe acute respiratory syndrome coronavirus 2, leading to the relatively low morbidity and mortality observed in the population.

Background: Immunization saves millions of lives, and globally, vaccines have significantly contributed to reducing mortality and morbidity due to more than 20 life-threatening illnesses. However, there are considerable disparities in vaccination coverage among countries and within populations. This study evaluates the reduction in disparities in vaccination coverage across various socio-economic groups by adopting an integrated community-engagement approach combined with maternal and child health services through mobile health camps. Methods: This secondary analysis is based on a community-based demonstration project conducted between 2014 and 2016 across 146 union councils in polio high-risk districts of Sindh, Khyber Pakhtunkhwa (KP) and Baluchistan in Pakistan. The intervention involved structured community engagement and mobile health camps providing routine immunization alongside maternal and child health services. Data were collected through cross-sectional independent surveys using the WHO two-stage cluster technique at the baseline and the endline, covering over 120,000 children under 5 years old. Four key outcome indicators were analyzed: fully vaccinated children, under-immunized children, unvaccinated children, and polio zero-dose children for equity in vaccine uptake. Results: The proportion of fully vaccinated children increased in the lowest wealth quintile from 28.5% (26.7%, 30.3%) at the baseline to 51.6% (49.5%, 53.8%) at the endline. In comparison, the increase in the richest quantities was 16.2% (14.0%, 18.4%) from the baseline 56.4% (54.6%, 58.2%) to the endline 72.7% (71.1%, 74.2%). Under-vaccination dropped by 10.2% (95% CI: −11.4%, −9.1%), with the poorest quintile showing an 11.8% reduction. The gap between the highest and lowest wealth quintiles in full immunization narrowed by 6.9%, from 27.9% to 21.0% at the baseline and the endline, respectively. The prevalence of zero-dose children significantly decreased across all quintiles, with the highest reduction observed in the lowest quintile of −11.3% (−13.6%, −9.1%). The difference between the highest and lowest wealth quintiles reduced from 6.2% to 3.8%. A significant reduction in polio zero-dose children was achieved, as 13.5% (95% CI: −14.8%, −12.2%), from 29.2% (95% CI: 28.0%, 30.3%) to 15.6% (14.8%, 16.5%). Conclusions: This study shows that integrating community engagement with maternal and child health services through health camps can significantly enhance immunization coverage and reduce wealth-based disparities in high-risk, hard-to-reach areas. The approach improved coverage for zero-dose and fully vaccinated children, suggesting a potential for scaling in regions with access issues, conflict, and vaccine hesitancy.

Background: The current polio epidemiology in Pakistan poses a unique challenge for global eradication, with polio transmission dynamics influenced by regional variations in immunity and disparities in immunization coverage. This study assesses the immunity level for all three poliovirus types among children aged 6–11 months in polio high-risk regions of Pakistan. Methods: Four consecutive rounds of cross-sectional serological surveys were conducted in polio high-risk areas of Pakistan between November 2016 and October 2023. Twelve high-risk areas were covered in the first three rounds of the survey, while 44 high-risk areas were covered in the fourth round. 25 clusters from each geographical stratum were selected utilizing probability proportional to size. Results: Across the four rounds of the survey, 32,907 children aged 6–11 months from 2084 clusters and 32,371 households were covered. Comparative analysis across the survey rounds showed that seroprevalence of poliovirus type 1 was high in provinces (>95%), albeit consistently lower in Balochistan (going down to 89.7% in Round 4). Type 2 seroprevalence was significantly lower and more heterogeneous, from 34.6% in Sindh to 83.4% in Punjab, with sharp declines by round 4, particularly in Balochistan (40.4%). Type 3 seroprevalence was overall high (>94% in Punjab, Sindh, and KPK) but dropped in the last round, while Balochistan exhibited continually lower immunity (81.1%). Conclusions: The findings reflect the variations in population immunity to poliovirus in the country, with notable fluctuations over the years. The gaps in type 2 immunity over time and consistently lowest in Balochistan highlight the need for continued monitoring of immunity levels and adaptable vaccination strategies.

Background: Milk feeding practices are a critical determinant of nutritional status in infancy, yet the relationship between specific milk feeding combinations and undernutrition remains poorly characterized in Pakistan, where animal milk use is widespread and the malnutrition burden is among the highest in South Asia. Methods: We pooled data on 96,736 children aged 6–23 months with valid anthropometry from 13 nationally and provincially representative cross-sectional surveys (2010–2020). Analyses were restricted to Punjab, Sindh, Khyber Pakhtunkhwa and Balochistan. Seven mutually exclusive feeding combinations were defined from 24 h dietary recall. Survey-weighted, age-stratified logistic regression (6–11 and 12–23 months) examined associations with stunting and wasting, adjusting progressively for area, household and child-level factors, with breastfeeding plus complementary feeding as the reference. Micronutrient deficiency data from NNS 2011 and NNS 2018 were analyzed descriptively. Results: Among infants aged 6–11 months, non-human milk (NHM) alone—predominantly unfortified buffalo or cow milk—was independently associated with elevated odds of stunting (OR: 1.54, 95% CI: 1.20–1.96) and wasting (OR: 1.86, 95% CI: 1.42–2.45) in fully adjusted models. Among children aged 12–23 months, NHM with complementary foods (NHM+CF) was independently protective against both stunting (OR: 0.73, 95% CI: 0.66–0.80) and wasting (OR: 0.80, 95% CI: 0.72–0.89). Household poverty was the strongest determinant of undernutrition in every stratum. Anemia (59.1%), ferritin deficiency (50.4%), iron deficiency anemia (33.0%) and vitamin D deficiency (63.1%) remained highly prevalent in 2018, and were highest in children receiving milk without complementary foods. In contrast, multiple micronutrient deficiency was elevated across most NHM-containing feeding groups regardless of complementary food status; after adjustment, NHM+CF and BM+NHM remained independently associated with multiple micronutrient deficiency at 12–23 months (OR: 1.35, 95% CI: 1.04–1.77 and OR: 1.52, 95% CI: 1.05–2.20, respectively). Conclusions: The nutritional correlates of NHM use are strongly age-dependent: adverse in the first year when it substitutes for breast milk without complementary foods, and favorable after 12 months as part of a diversified diet. Feeding interventions should be embedded within poverty-reduction frameworks. All data were cross-sectional, so these associations are not causal.

Background: The current polio epidemiology in Pakistan poses a unique challenge for global eradication, with polio transmission dynamics influenced by regional variations in immunity and disparities in immunization coverage. This study assesses the immunity level for all three poliovirus types among children 6-11 months in polio high-risk regions of Pakistan. Methods: Four consecutive rounds of cross-sectional serological surveys were conducted in polio high-risk areas of Pakistan between November 2016 and October 2023. 12 high-risk areas were covered in the first three rounds of the survey, while 44 high-risk areas were covered in the fourth round. 25 clusters from each geographical stratum were selected utilizing probability proportional to size. Results: Across the four rounds of the survey, 32,907 children aged 6–11 months from 2,084 clusters and 32,371 households were covered. Temporal analysis showed that seroprevalence of poliovirus type 1 was high in provinces (>95%), albeit consistently lower in Balochistan (going down to 89.7% in Round 4). Type 2 seroprevalence was significantly lower and more heterogeneous, from 34.6% in Sindh to 83.4% in Punjab, with sharp declines by Round 4, particularly in Balochistan (40.4%). Type 3 seroprevalence was overall high (>94% in Punjab, Sindh, and KPK) but dropped in the last round, while Balochistan exhibited continually lower immunity (81.1%). Conclusion: The findings reflect the variations in population immunity to poliovirus in the country, with notable fluctuations over the years. The gaps in type 2 immunity over time and consistently lowest in Balochistan highlight the need for continued monitoring of immunity levels and adaptable vaccination strategies.

Background According to the World Health Organization (WHO), worldwide anemia prevalence in children of 6–59 months is 40% [1]. Though iron deficiency is recognized as a significant cause of anemia, vitamin B₁₂ (B₁₂) and folate deficiencies are also important causes. The previous Pakistan National Nutrition Survey (NNS) 2011 showed a high prevalence among women of reproductive age (WRA), which necessitated further investigation in follow-up surveys among children. Methods We performed a secondary analysis of the National Nutrition Survey (NNS) 2018–2019. Blood samples were obtained from 31,828 children (< 5 years), with a subsample analyzed for B₁₂ (n=2693) and folate (n=6690) deficiency. B₁₂ was assessed by electrochemiluminescence immunoassay, and folate by CDC’s microbiologic assay. Logistic regressions were applied to determine factors associated with deficiency. Results 35.1%, while 24.8% of children showed folate and B₁₂ deficiency, respectively. Higher odds of folate and B₁₂ deficiency were observed in Khyber Pakhtunkhwa, OR = 1.424 (95% CI 1.157, 1.752), and newly merged districts of Khyber Pakhtunkhwa, OR = 11.257 (95% CI 2.291, 55.314), respectively. Additionally, mother’s education was associated with B₁₂ deficiency i.e. uneducated OR = 2.017, (95% CI 1.229, 3.308), primary OR = 2.361 (95% CI 1.359, 4.103) and middle OR = 2.108 (95% CI 1.144, 3.882) while underweight was associated with folate deficiency only, OR = 1.181 (95% CI 1.016, 1.371). Conclusion This analysis highlights a considerable burden of folate (35.1%) and vitamin B₁₂ (24.8%) deficiencies among Pakistani children under five years of age, with regional disparities. Socioeconomic and nutritional factors, particularly maternal education and child undernutrition, further influence the risk of deficiency. These results emphasize the need for region-specific nutrition interventions, maternal education programs, and strengthened food fortification strategies.