You are presented with a paragraph from a COVID-19 literature. Classify the topics of this piece of text by choosing from the following categories:

- Epidemic Forecasting: The content relates to predictions about the spread of COVID-19.
- Treatment: The paragraph discusses therapeutic methods or medication for COVID-19.
- Prevention: The content covers measures to prevent the spread of COVID-19.
- Mechanism: The paragraph explains the biological mechanisms of the virus.
- Case Report: The content is a report of a COVID-19 case.
- Transmission: The paragraph discusses how COVID-19 is transmitted.
- Diagnosis: The content is about diagnosing COVID-19 in individuals.

Your classification should be provided as an element within a JSON array. The array should be formatted with topics enclosed in double quotes and separated by commas, following the JSON format, for example: ["Topic1", "Topic2", ...]. Include all applicable topics within the array. Your output should be a valid JSON array, and no additional text should be included in your response.

Article:

The COVID-19 pandemic has highlighted global oxygen system deficiencies and revealed gaps in how we understand and measure 'oxygen access'. We present a case study on oxygen access from 58 health facilities in Lagos state, Nigeria. We found large differences in oxygen access between facilities (primary vs secondary, government vs private) and describe three key domains to consider when measuring oxygen access: availability, cost, use. Of 58 facilities surveyed, 8 (14%) of facilities had a functional pulse oximeter. Oximeters (N=27) were typically located in outpatient clinics (12/27, 44%), paediatric ward (6/27, 22%) or operating theatre (4/27, 15%). 34/58 (59%) facilities had a functional source of oxygen available on the day of inspection, of which 31 (91%) facilities had it available in a single ward area, typically the operating theatre or maternity ward. Oxygen services were free to patients at primary health centres, when available, but expensive in hospitals and private facilities, with the median cost for 2 days oxygen 13 000 (US$36) and 27 500 (US$77) Naira, respectively. We obtained limited data on the cost of oxygen services to facilities. Pulse oximetry use was low in secondary care facilities (32%, 21/65 patients had SpO2 documented) and negligible in private facilities (2%, 3/177) and primary health centres (<1%, 2/608). We were unable to determine the proportion of hypoxaemic patients who received oxygen therapy with available data. However, triangulation of existing data suggested that no facilities were equipped to meet minimum oxygen demands. We highlight the importance of a multifaceted approach to measuring oxygen access that assesses access at the point-of-care and ideally at the patient-level. We propose standard metrics to report oxygen access and describe how these can be integrated into routine health information systems and existing health facility assessment tools.
["Prevention"]