Epidemiological impact of a large number of false negative SARS-CoV-2 test results in South West England during September and October 2021.

During September and October 2021, a substantial number of Polymerase Chain Reaction (PCR) tests in England processed at a single laboratory were incorrectly reported as negative. We estimate the number of false negative test results issued and investigate the epidemiological impact of this incident. We estimate the number of COVID-19 cases that would have been reported had the sensitivity of the laboratory test procedure not dropped for the period 2 September to 12 October. In addition, by making comparisons between the most affected local areas and comparator populations, we estimate the number of additional infections, cases, hospitalisations and deaths that could have occurred as a result of increased transmission due to false negative test results.We estimate that around 39,000 tests may have been false negatives during this period and, as a direct result of this incident, the most affected areas in the South-West of England could have experienced between 6000 and 34,000 additional reportable cases, with a central estimate of around 24,000 additional reportable cases. Using modelled relationships between key variables, we estimate that this central estimate could have translated to approximately 55,000 additional infections.Each false negative likely led to around 1.5 additional infections. The incident is likely to have had a measurable impact on cases and infections in the affected areas in the South-West of England. IMPACT STATEMENT: These results indicate the significant negative impact of incorrect testing on COVID outcomes; and make a substantial contribution to understanding the impact of testing systems and the need to ensure high accuracy in testing and reporting of results.

Adolescents' reported usage of selected foods in relation to their perceptions and social norms for those foods.

This paper reports a study of factors associated with the consumption of 22 diverse foods among 2082 students aged 12-15 years in Tasmania, Australia. Students provided data by completing a printed questionnaire. Multiple linear regression was used to assess how well self-reported usual (past) frequency of consumption of a food could be estimated from their perceptions of the qualities of the food (their liking for it, its healthfulness) and their descriptive social norms for the food (its usage by parents and its usage by friends). For all foods, multiple R was significant (p < 0.0001), with values ranging from 0.28-0.64 (median for the 22 foods being 0.49). Standardized regression coefficients for liking and parental usage were highly significant (p < 0.0001) for all foods. However, consistently lower coefficients were found for friends' usage (11 with p < 0.01, but only three with p < 0.0001) and healthfulness (five with p < 0.01, but only one with p < 0.0001). The absolute and relative magnitudes of the regression coefficients varied substantially between the foods. Liking was a stronger predictor than parental usage for 11 of the foods, and parental usage out-ranked liking for the remaining 11. Regression coefficients for friends' usage and healthfulness were smaller than those for liking and parental usage for all foods studied.

The importance of measured intake in assessing exposure of breast-fed infants to organochlorines.

OBJECTIVES: To estimate infants' intake of organochlorines (OCs) from their measured intake of breast milk; to compare these with the acceptable daily intakes (ADIs) set by the World Health Organization (WHO). DESIGN: Primiparous nursing mothers were recruited from either an industrial or rural area between January and November 1992. SETTING: Mothers volunteered in response to information displayed at their Infant Welfare Centre. All sampling was undertaken in the subject's home. SUBJECTS: The sole entry criterion was primiparity. Three breast milk samples were collected at one month intervals from each mother. OC levels were measured on a milk fat basis by gas chromatograph-mass spectrometer and individual milk intakes were used to determine the infant's daily OC intake. Of the 23 mothers who entered the study, 17 finished, resulting in 57 samples for intake determination. RESULTS: Some intakes of hexachlorobenzene (HCB), chlordane, dieldrin and heptachlor epoxide (HE) exceeded the ADI. High OC levels in breast milk did not necessarily result in a high intake for the infant. CONCLUSIONS: Assessment of the exposure of infants to OC contaminants in breast milk requires an accurate estimate of OC intake. Intakes estimated using inferred rather than measured values for milk fat and milk intake are not reliable indicators of actual intakes.

Selenium and human lactation in Australia: milk and blood selenium levels in lactating women, and selenium intakes of their breast-fed infants.

A series of 20 mother-infant pairs were studied in Brisbane, Australia, at 6-12 weeks postpartum. The mean selenium concentration in maternal blood was 101 (SD +/- 19) ng/g and in maternal serum 81(+/- 15) ng/g; serum values appeared low in comparison with those reported for lactating women from Japan and the USA, but similar to those from Finland and from a previous Australian study. Breast milk selenium concentrations (11.9 +/- 3.5 ng/g) were also low by international standards, but not as low as in New Zealand or Scandinavia. There was no correlation between selenium concentrations in milk and blood (or serum). The infants' 24-h breast-milk intakes were 856 +/- 172 g, and their 24-h selenium intakes 10.7 +/- 4.1 micrograms (compared to the Australian RDI of 10 micrograms).

A comparison of two methods of breastfeeding management.

This study has demonstrated that, in a small group of 58 mothers, specific advice focused on establishing easier patterns of breastfeeding resulted in more of them continuing to breastfeed their babies for a longer period post-partum, with a less intense feeding pattern and the use of fewer complementary bottles of formula or other liquids, than did those given only the standard advice about breastfeeding. Current advice might be reviewed to continue to encourage demand breastfeeding but to emphasise the establishment of easier patterns of breastfeeding that optimise the mother-infant interaction.

Do ambient temperature and humidity influence the breast-milk intake of babies?

This study explored the possible effect of ambient temperature and humidity on the breast-milk intakes of Australian infants (n = 35) aged 6-12 weeks. Over a 24 h period, each baby was fed only on milk from the breast; milk intakes, temperature and humidity were monitored. Milk intakes--determined by test-weighing the baby, with a correction for evaporative losses during feeds--showed a mean of 830 g/24 h, with median 818 and s.d. 152. The mean correction for evaporative losses was 46 g/24 h; omission of this correction would have led to an average underestimate of 5.5% in 24 h intakes. Ambient conditions varied substantially between subjects: 24 h mean temperatures ranged from 14 to 28 degrees C, and humidities from 48 to 97%. Over these ranges, breast-milk intakes did not appear to be significantly influenced by ambient temperature or ambient humidity; however, the rate of evaporative losses increased by 0.008 g/min for each 1 degree C rise in ambient temperature.

Trace elements in human milk.

Presented is a study, using multielement neutron activation analysis, of the elemental composition of blood plasma and milk in a group of lactating Australian women. Having established baseline values for nine elements, the authors studied factors affecting concentrations in milk and the partitioning of those elements between plasma and milk. Changes in this partitioning with the progression of lactation were demonstrated, and their nutritional implications for the exclusively breast-fed baby discussed. Progestogen-only oral contraceptives had no significant effect on levels of any of the trace elements in either blood or milk.

Changes in plasma vitamin A in lactating and non-lactating oral contraceptive users.

Plasma vitamin A and retinol-binding protein (RBP) concentrations have been studied in women using oral contraceptives (OC) for up to 4 years. In eight women taking an oestrogenic OC(1 mg of norethisterone acetate + 50 micrograms of ethinyloestradiol) values almost doubled within 6 months, but diminished somewhat after 4 years. Saturation of RBP with retinol remained fairly constant. Five lactating women who took progestogen-only OC (30 micrograms of levonorgestrel or 350 micrograms of norethisterone) showed no significant alteration in plasma vitamin A or RBP concentrations as compared with nine lactating non-OC users. All lactating women showed significant differences between the highest and lowest plasma vitamin A (P less than 0.005) and RBP (P less than 0.05) concentrations during the first 6 months of lactation. Highest values occurred 11-12 weeks postpartum and the lowest at 15-17 weeks. Percentage saturation of RBP with retinol was significantly higher (P less than 0.005) when vitamin A concentration was highest.

Effect of oral contraceptive use on ascorbic acid and vitamin A in lactation.

PIP: A large prospective study is being undertaken on the effects of OCs (oral contraceptives) on vitamins and trace elements in the plasma and milk of lactating women. Results presented here are of progestagen-only OC effects on ascorbic acid and vitamin A in the plasma and milk of 5 volunteers. 3 of the women took 350 mcg norethisterone and the other 2 took 30 mcg levonorgestrel daily. Their pretherapy age, height, weight, dietary data, and breast feeding history were recorded. Blood samples and fasting milk samples were taken for 19 weeks and the results graphed and analyzed. Findings of the study in general suggest that progestagen-only OCs have little or not effect on milk or plasma levels of vitamin A and ascorbic acid. Actual results show little change in plasma ascorbic acid but a slight, nonsignificant, decrease in milk ascorbic acid levels. Supplementation with ascorbic acid pills promptly increased milk ascorbic acid levels. Milk fluctuations were greater for vitamin A than for ascorbic acid. There was little weekly variation in plasma vitamin A. Changes in vitamin A and ascorbic acid levels were also observed in 9 breast feeding women who were not taking OCs. The lack of effect was expected since most changes in vitamin status have been attributed to estrogen content of OCs.^ieng