SELECT donors.id                        AS donor_id,
       donor_visits.age                 AS age,
       donor_visits.vaccine_resp        AS outcome,
       donor_visits.visit_id            AS visit,
       donor_visits.visit_day           AS day,
       donor_visits.visit_year          AS year
       # experimental_data.name_formatted AS data_name,
       # experimental_data.data           AS data,
FROM   donors
       LEFT JOIN donor_visits
              ON donors.id = donor_visits.donor_id
                 # AND donor_visits.visit_id = 1
       # INNER JOIN experimental_data
       #         ON donor_visits.id = experimental_data.donor_visits_id
       #            AND experimental_data.donor_id = donor_visits.donor_id
WHERE  donors.gender IS NOT NULL
       AND donor_visits.vaccine = 4
ORDER  BY donors.id DESC