How often have worldwide news articles linked to URLs on the CDC and WHO websites? Using the Global Knowledge Graph (GKG)'s outlinks data, captured since April 2016, it requires just a single SQL query to search all of the outlinks found in the body text of each article this year:

SELECT SUBSTR(CAST(DATE AS STRING), 0, 8) DAY, count(distinct DocumentIdentifier) CNT FROM `gdelt-bq.gdeltv2.gkg_partitioned` WHERE LOWER(Extras) like '%cdc.gov%' and DATE(_PARTITIONTIME) >= "2020-01-01" GROUP BY DAY ORDER BY DAY ASC
SELECT SUBSTR(CAST(DATE AS STRING), 0, 8) DAY, count(distinct DocumentIdentifier) CNT FROM `gdelt-bq.gdeltv2.gkg_partitioned` WHERE LOWER(Extras) like '%who.int%' and DATE(_PARTITIONTIME) >= "2020-01-01" GROUP BY DAY ORDER BY DAY ASC

The final graph can be seen below, showing that Feb. 25 marked the beginning of the main surge of links, peaking on Mar. 12 for WHO and Mar. 13 for the CDC. The CDC has been cited far more often than the WHO, which makes sense, since the news outlets in most countries likely link to their local domestic health agencies rather than the international WHO, since their local agencies reflect the laws, regulations and guidance specific to each country.