* pregnancy or breastfeeding * ongoing antiviral or antiretroviral treatment * known history of hiv * ongoing anti-inflammatory treatment that cannot be temporarily discontinued during the study. this includes nonsteroidal anti-inflammatory drugs (nsaids), and corticosteroids - including dexamethasone (dexamethasone administration restricted to recommended standard of care use per nih covid-19 guidelines) 1. drugs dependent on gastric ph for absorption, e.g., dasatinib, delavirdine, mesylate, cefditoren, and fosamprenavir; 2. tizanidine (cyp1a2) substrate; 3. drugs that interfere with hemostasis (e.g., warfarin, aspirin, selective serotonin reuptake inhibitors \[ssris\]/serotonin norepinephrine reuptake inhibitors (snris\]); 4. angiotensin converting enzyme (ace) inhibitors, angiotensin receptor blockers (arb), or beta-blockers; 5. diuretics; 6. digoxin * ongoing treatment that cannot be temporarily discontinued during the study, with: antimalarials, antiarrhythmics, tricyclic antidepressants, natalizumab, quinolones, macrolides, agalsidase alfa and beta * ongoing famotidine or celecoxib or other covid-19 clinical investigational treatment(s) within the past 30 days, or current participation in another investigational clinical trial * history of asthma, urticaria, or other allergic-type reactions after taking aspirin or other nsaids * history of immunosuppression * rejection of participation by principal investigator or sponsor * any contraindication for famotidine or celecoxib treatment: 1. famotidine or celecoxib hypersensitivity 2. retinopathy, visual field or visual acuity disturbances 3. history of cardiovascular disease, such as congestive heart failure, qt prolongation, myocardial infarction, bradycardia (\<50 bpm), ventricular tachycardia, other arrhythmias 4. myasthenia gravis 5. psoriasis or porphyria 6. history of renal failure/dialysis or a glomerular clearance \<60 ml/min 7. history of severe hypoglycemia 8. moderate or severe hepatic impairment, e.g., child-pugh class b or c 9. known or suspected to be poor cyp2c9 metabolizers based on genotype or previous history or experience with other cyp2c9 substrates, such as warfarin and phenytoin

* pregnancy or breastfeeding * ongoing antiviral or antiretroviral treatment * known history of hiv * ongoing anti-inflammatory treatment that cannot be temporarily discontinued during the study. this includes nonsteroidal anti-inflammatory drugs (nsaids), and corticosteroids - including dexamethasone (dexamethasone administration restricted to recommended standard of care use per nih covid-19 guidelines) 1. drugs dependent on gastric ph for absorption, e.g., dasatinib, delavirdine, mesylate, cefditoren, and fosamprenavir; 2. tizanidine (cyp1a2) substrate; 3. drugs that interfere with hemostasis (e.g., warfarin, aspirin, selective serotonin reuptake inhibitors \[ssris\]/serotonin norepinephrine reuptake inhibitors (snris\]); 4. angiotensin converting enzyme (ace) inhibitors, angiotensin receptor blockers (arb), or beta-blockers; 5. diuretics; 6. digoxin * ongoing treatment that cannot be temporarily discontinued during the study, with: antimalarials, antiarrhythmics, tricyclic antidepressants, natalizumab, quinolones, macrolides, agalsidase alfa and beta * ongoing famotidine or celecoxib or other covid-19 clinical investigational treatment(s) within the past 30 days, or current participation in another investigational clinical trial * history of asthma, urticaria, or other allergic-type reactions after taking aspirin or other nsaids * history of immunosuppression * rejection of participation by principal investigator or sponsor * any contraindication for famotidine or celecoxib treatment: 1. famotidine or celecoxib hypersensitivity 2. retinopathy, visual field or visual acuity disturbances 3. history of cardiovascular disease, such as congestive heart failure, qt prolongation, myocardial infarction, bradycardia (\<50 bpm), ventricular tachycardia, other arrhythmias 4. myasthenia gravis 5. psoriasis or porphyria 6. history of renal failure/dialysis or a glomerular clearance \<60 ml/min 7. history of severe hypoglycemia 8. moderate or severe hepatic impairment, e.g., child-pugh class b or c 9. known or suspected to be poor cyp2c9 metabolizers based on genotype or previous history or experience with other cyp2c9 substrates, such as warfarin and phenytoin

pregnancy or breastfeeding ongoing antiviral or antiretroviral treatment known history of hiv ongoing anti-inflammatory treatment that cannot be temporarily discontinued during the study. this includes nonsteroidal anti-inflammatory drugs (nsaids), and corticosteroids - including dexamethasone (dexamethasone administration restricted to recommended standard of care use per nih covid-19 guidelines) drugs dependent on gastric ph for absorption, e.g., dasatinib, delavirdine, mesylate, cefditoren, and fosamprenavir; tizanidine (cyp1a2) substrate; drugs that interfere with hemostasis (e.g., warfarin, aspirin, selective serotonin reuptake inhibitors [ssris]/serotonin norepinephrine reuptake inhibitors (snris]); angiotensin converting enzyme (ace) inhibitors, angiotensin receptor blockers (arb), or beta-blockers; diuretics; digoxin ongoing treatment that cannot be temporarily discontinued during the study, with: antimalarials, antiarrhythmics, tricyclic antidepressants, natalizumab, quinolones, macrolides, agalsidase alfa and beta ongoing famotidine or celecoxib or other covid-19 clinical investigational treatment(s) within the past 30 days, or current participation in another investigational clinical trial history of asthma, urticaria, or other allergic-type reactions after taking aspirin or other nsaids history of immunosuppression rejection of participation by principal investigator or sponsor any contraindication for famotidine or celecoxib treatment: famotidine or celecoxib hypersensitivity retinopathy, visual field or visual acuity disturbances history of cardiovascular disease, such as congestive heart failure, qt prolongation, myocardial infarction, bradycardia (<50 bpm), ventricular tachycardia, other arrhythmias myasthenia gravis psoriasis or porphyria history of renal failure/dialysis or a glomerular clearance <60 ml/min history of severe hypoglycemia moderate or severe hepatic impairment, e.g., child-pugh class b or c known or suspected to be poor cyp2c9 metabolizers based on genotype or previous history or experience with other cyp2c9 substrates, such as warfarin and phenytoin

pregnancy or breastfeeding ongoing antiviral or antiretroviral treatment known history of hiv ongoing anti-inflammatory treatment that cannot be temporarily discontinued during the study. this includes nonsteroidal anti-inflammatory drugs (nsaids), and corticosteroids - including dexamethasone (dexamethasone administration restricted to recommended standard of care use per nih covid-19 guidelines) drugs dependent on gastric ph for absorption, e.g., dasatinib, delavirdine, mesylate, cefditoren, and fosamprenavir; tizanidine (cyp1a2) substrate; drugs that interfere with hemostasis (e.g., warfarin, aspirin, selective serotonin reuptake inhibitors [ssris]/serotonin norepinephrine reuptake inhibitors (snris]); angiotensin converting enzyme (ace) inhibitors, angiotensin receptor blockers (arb), or beta-blockers; diuretics; digoxin ongoing treatment that cannot be temporarily discontinued during the study, with: antimalarials, antiarrhythmics, tricyclic antidepressants, natalizumab, quinolones, macrolides, agalsidase alfa and beta ongoing famotidine or celecoxib or other covid-19 clinical investigational treatment(s) within the past 30 days, or current participation in another investigational clinical trial history of asthma, urticaria, or other allergic-type reactions after taking aspirin or other nsaids history of immunosuppression rejection of participation by principal investigator or sponsor any contraindication for famotidine or celecoxib treatment: famotidine or celecoxib hypersensitivity retinopathy, visual field or visual acuity disturbances history of cardiovascular disease, such as congestive heart failure, qt prolongation, myocardial infarction, bradycardia (<50 bpm), ventricular tachycardia, other arrhythmias myasthenia gravis psoriasis or porphyria history of renal failure/dialysis or a glomerular clearance <60 ml/min history of severe hypoglycemia moderate or severe hepatic impairment, e.g., child-pugh class b or c known or suspected to be poor cyp2c9 metabolizers based on genotype or previous history or experience with other cyp2c9 substrates, such as warfarin and phenytoin

- pregnancy or breastfeeding - ongoing antiviral or antiretroviral treatment - known history of hiv - ongoing anti-inflammatory treatment that cannot be temporarily discontinued during the study. this includes nonsteroidal anti-inflammatory drugs (nsaids), and corticosteroids - including dexamethasone (dexamethasone administration restricted to recommended standard of care use per nih covid-19 guidelines) 1. drugs dependent on gastric ph for absorption, e.g., dasatinib, delavirdine, mesylate, cefditoren, and fosamprenavir; 2. tizanidine (cyp1a2) substrate; 3. drugs that interfere with hemostasis (e.g., warfarin, aspirin, selective serotonin reuptake inhibitors [ssris]/serotonin norepinephrine reuptake inhibitors (snris]); 4. angiotensin converting enzyme (ace) inhibitors, angiotensin receptor blockers (arb), or beta-blockers; 5. diuretics; 6. digoxin - ongoing treatment that cannot be temporarily discontinued during the study, with: antimalarials, antiarrhythmics, tricyclic antidepressants, natalizumab, quinolones, macrolides, agalsidase alfa and beta - ongoing famotidine or celecoxib or other covid-19 clinical investigational treatment(s) within the past 30 days, or current participation in another investigational clinical trial - history of asthma, urticaria, or other allergic-type reactions after taking aspirin or other nsaids - history of immunosuppression - rejection of participation by principal investigator or sponsor - any contraindication for famotidine or celecoxib treatment: 1. famotidine or celecoxib hypersensitivity 2. retinopathy, visual field or visual acuity disturbances 3. history of cardiovascular disease, such as congestive heart failure, qt prolongation, myocardial infarction, bradycardia (<50 bpm), ventricular tachycardia, other arrhythmias 4. myasthenia gravis 5. psoriasis or porphyria 6. history of renal failure/dialysis or a glomerular clearance <60 ml/min 7. history of severe hypoglycemia 8. moderate or severe hepatic impairment, e.g., child-pugh class b or c 9. known or suspected to be poor cyp2c9 metabolizers based on genotype or previous history or experience with other cyp2c9 substrates, such as warfarin and phenytoin

- pregnancy or breastfeeding - ongoing antiviral or antiretroviral treatment - known history of hiv - ongoing anti-inflammatory treatment that cannot be temporarily discontinued during the study. this includes nonsteroidal anti-inflammatory drugs (nsaids), and corticosteroids - including dexamethasone (dexamethasone administration restricted to recommended standard of care use per nih covid-19 guidelines) 1. drugs dependent on gastric ph for absorption, e.g., dasatinib, delavirdine, mesylate, cefditoren, and fosamprenavir; 2. tizanidine (cyp1a2) substrate; 3. drugs that interfere with hemostasis (e.g., warfarin, aspirin, selective serotonin reuptake inhibitors [ssris]/serotonin norepinephrine reuptake inhibitors (snris]); 4. angiotensin converting enzyme (ace) inhibitors, angiotensin receptor blockers (arb), or beta-blockers; 5. diuretics; 6. digoxin - ongoing treatment that cannot be temporarily discontinued during the study, with: antimalarials, antiarrhythmics, tricyclic antidepressants, natalizumab, quinolones, macrolides, agalsidase alfa and beta - ongoing famotidine or celecoxib or other covid-19 clinical investigational treatment(s) within the past 30 days, or current participation in another investigational clinical trial - history of asthma, urticaria, or other allergic-type reactions after taking aspirin or other nsaids - history of immunosuppression - rejection of participation by principal investigator or sponsor - any contraindication for famotidine or celecoxib treatment: 1. famotidine or celecoxib hypersensitivity 2. retinopathy, visual field or visual acuity disturbances 3. history of cardiovascular disease, such as congestive heart failure, qt prolongation, myocardial infarction, bradycardia (<50 bpm), ventricular tachycardia, other arrhythmias 4. myasthenia gravis 5. psoriasis or porphyria 6. history of renal failure/dialysis or a glomerular clearance <60 ml/min 7. history of severe hypoglycemia 8. moderate or severe hepatic impairment, e.g., child-pugh class b or c 9. known or suspected to be poor cyp2c9 metabolizers based on genotype or previous history or experience with other cyp2c9 substrates, such as warfarin and phenytoin