PubMed:
Provider: NLM
Database: PubMed (National Library of Medicine), https://pubmed.ncbi.nlm.nih.gov
Date(s) Searched: October 28, 2026
Final count: 96 (line 4)
Search Terms:

No. | Query | Results | Reported
1 | "COVID-19"[Majr] OR "long COVID"[tiab] | 264,927 |
2 | "Cognitive Dysfunction"[Mesh] OR "brain fog"[tiab] | 58,856 |
3 | "COVID-19 Vaccines"[Mesh] OR vaccin*[tiab] | 510,993 |
4 | 1 AND 2 AND 3 | 96 |

Final query as run through NCBI E-utilities (line 4):
("COVID-19"[Majr] OR "long COVID"[tiab]) AND ("Cognitive Dysfunction"[Mesh] OR "brain fog"[tiab]) AND ("COVID-19 Vaccines"[Mesh] OR vaccin*[tiab])

AI-use statement:
No generative AI model was used: the strategy was supplied by the searcher and checked with the PICO search builder. Every MeSH heading, Supplementary Concept and publication type was looked up in NLM MeSH (id.nlm.nih.gov): 3 valid. Every line was run in PubMed through NCBI E-utilities on October 28, 2026, and its count compared with the count written in the strategy.

Run 8b2c8b17-5f2f-4551-b222-cee75c498151, exported October 29, 2026 from the PICO search builder.