Participants will self-administer matching placebo, intranasally, twice per week for 4 weeks as a flexible dose regimen in the Double-Blind Induction Phase.

Duloxetine could be selected as the oral antidepressant medication by the investigator based on review of Massachusetts General Hospital - Antidepressant Treatment Response Questionnaire (MGH-ATRQ) and relevant prior antidepressant medication information. The minimum therapeutic dose is 60 milligram per day (mg/day).

Escitalopram could be selected as the oral antidepressant medication by the investigator based on review of MGH-ATRQ and relevant prior antidepressant medication information. Escitalopram will be titrated upto a dose of 20 mg/day, but if not tolerated the dose can be reduced to the minimum therapeutic dose of 10 mg/day.

Sertraline could be selected as the oral antidepressant medication by the investigator based on review of MGH-ATRQ and relevant prior antidepressant medication information. Sertraline will be titrated upto a dose of 150 mg/day, but if not tolerated the dose can be reduced to the minimum therapeutic dose of 50 mg/day.

Venlafaxine Extended Release could be selected as the oral antidepressant medication by the investigator based on review of MGH-ATRQ and relevant prior antidepressant medication information. Venlafaxine Extended Release will be titrated upto a dose of 225 mg/day, but if not tolerated the dose can be reduced to the minimum therapeutic dose of 150 mg/day.

The SDS is a participant-reported outcome measure and 5 item questionnaire used for assessment of functional impairment and associated disability. First three items assess disruption of 1 work/school, 2 social life, 3 family life/home responsibilities using a 0(no impairment)-10 (most severe impairment). Score for first 3 items are summed to create total score of 0-30 where higher score indicates greater impairment and a negative change in score indicates improvement. It also has one item on days lost from school or work and one item on days when under productive.

The SDS is a participant-reported outcome measure and 5 item questionnaire used for assessment of functional impairment and associated disability. First three items assess disruption of 1 work/school, 2 social life, 3 family life/home responsibilities using a 0(no impairment)-10 (most severe impairment). Score for first 3 items are summed to create total score of 0-30 where higher score indicates greater impairment and a negative change in score indicates improvement. It also has one item on days lost from school or work and one item on days when under productive. The last post baseline observation during the phase was carried forward as "End Point" for that phase.

PHQ-9 is 9-item, self-report scale assessing depressive symptoms. Each item is rated on 4-point scale (0=Not at all, 1=Several Days, 2=More than half days, 3=Nearly every day. Scale scores each of 9 symptom domains of Diagnostic and Statistical Manual of Mental Disorders, Major Depressive Disorder criteria and it has been used both as screening tool and measure of response to treatment for depression. The participant's item responses are summed to provide a total score (range of 0 to 27) with higher scores indicating greater severity of depressive symptoms. Severity of PHQ-9 categorized as follows: None-minimal (0-4), Mild (5-9), Moderate (10-14), Moderately Severe (15-19), Severe (20-27).

PHQ-9 is 9-item, self-report scale assessing depressive symptoms. Each item is rated on 4-point scale (0=Not at all, 1=Several Days, 2=More than half days, 3=Nearly every day). Scale scores each of 9 symptom domains of Diagnostic and Statistical Manual of Mental Disorders, Major Depressive Disorder criteria and it has been used both as screening tool and measure of response to treatment for depression. The participant's item responses are summed to provide a total score (range of 0 to 27) with higher scores indicating greater severity of depressive symptoms. Severity of PHQ-9 categorized as follows: None-minimal (0-4), Mild (5-9), Moderate (10-14), Moderately Severe (15-19), Severe (20-27). The last post baseline observation during the phase was carried forward as "End Point" for that phase.

MADRS is clinician-rated scale designed to measure depression severity, and to detect changes due to antidepressant treatment. Scale consists of 10 items (apparent sadness, reported sadness, inner tension, sleep, appetite, concentration, lassitude, interest level, pessimistic thoughts, and suicidal thoughts), each of which is scored from 0 (item is not present or is normal) to 6 (severe or continuous presence of symptoms), summed for a total possible score of 0 to 60. Higher scores represent more severe condition. The percentage of participants with greater than or equal to (>=) 50 % reduction from baseline in MADRS total score was reported. The last post baseline observation during the phase was carried forward as "End Point" for that phase.

Remission was defined as participants who had a MADRS total score of less than or equal to (=<) 12. MADRS is clinician-rated scale designed to measure depression severity, and to detect changes due to antidepressant treatment. Scale consists of 10 items (apparent sadness, reported sadness, inner tension, sleep, appetite, concentration, lassitude, interest level, pessimistic thoughts, and suicidal thoughts), each of which is scored from 0 (item is not present or is normal) to 6 (severe or continuous presence of symptoms), summed for a total possible score of 0 to 60. Higher scores represent more severe condition. The last post baseline observation during the phase was carried forward as "End Point" for that phase.

Response defined as SDS total score <= 12 and individual item scores each <= 4. SDS is a participant-reported outcome measure and 5 item questionnaire used for assessment of functional impairment and associated disability. First three items assess disruption of 1 work/school, 2 social life, 3 family life/home responsibilities using a 0(no impairment)-10 (most severe impairment). Score for first 3 items are summed to create total score of 0-30 where higher score indicates greater impairment and a negative change in score indicates improvement. It also has one item on days lost from school or work and one item on days when under productive.

Remission defined as SDS total score <= 6 and individual item scores each <= 2. SDS is a participant reported outcome measure and is a 5-item questionnaire which has been widely used and accepted for assessment of functional impairment and associated disability. The first three items assess disruption of (1) work/school, (2) social life, and (3) family life/home responsibilities using a 0-10 rating scale. The score for the first three items were summed to create a total score of 0-30 where a higher score indicates greater impairment. It also has one item on days lost from school or work and one item on days when under productive.

CGI-S provides measure of severity of participant's illness including participant's history, psychosocial circumstances, symptoms, behavior and impact of symptoms on ability to function. CGI-S evaluates severity of psychopathology on scale of 0 to 7. Considering total clinical experience, participant is assessed on severity of mental illness according to: 0=not assessed; 1=normal (not at all ill); 2=borderline mentally ill; 3=mildly ill; 4=moderately ill; 5=markedly ill; 6=severely ill; 7=among most extremely ill patients. CGI-S permits global evaluation of participant's condition at given time. The last post baseline observation during the phase was carried forward as "End Point" for that phase.

GAD-7 is a brief and validated 7-item self-report assessment of overall anxiety. Participants respond to each item using a 4-point scale with response categories of 0=not at all, 1=several days, 2=more than half the days, and 3=nearly every day. Item responses are summed to yield a total score with a range of 0 to 21, where higher scores indicate more anxiety. The recall period is 2 weeks. The severity of the GAD-7 is categorized as follows: None (0-4), Mild (5-9), Moderate (10-14) and Severe (15 -21). The last post baseline observation during the phase was carried forward as "End Point" for that phase.

European Quality of Life Group-5 Dimension-5-Level (EQ-5D-5L) is a 2-part instrument for use as a measure of health outcome, designed for self-completion by respondents. It consists of EQ-5D-5L descriptive system and EQ VAS. EQ-5D-5L descriptive system comprises of 5 dimensions: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each has 5 levels of perceived problems (1-no problem, 2-slight problems, 3-moderate problems, 4-severe problems, 5-extreme problems). Participant selects answer for each of 5 dimensions considering response that best matches his/her health "today". Responses were used to generate a Health Status Index (HSI). Health Status Index range is -0.148 - 0.949, is anchored at 0 (dead) and 1 (full health).

EQ-5D-5L is a 2-part instrument for use as a measure of health outcome, designed for self-completion by respondents. It consists of EQ-5D-5L descriptive system and EQ VAS. The EQ VAS self-rating records the respondent's own assessment of his or her overall health status at the time of completion, on a scale of 0 (the worst health you can imagine) to 100 (the best health you can imagine).

EQ-5D-5L consists of EQ-5D-5L descriptive system and EQ visual analogue scale (EQ VAS). EQ-5D-5L descriptive system comprises of 5 dimensions: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each has 5 levels of perceived problems (1-no problem, 2-slight problems, 3-moderate problems, 4-severe problems, 5-extreme problems). Participant selects answer for each of 5 dimensions considering response that best matches his/her health "today". Responses were used to generate a Health Status Index (HSI). Health Status Index range is -0.148 - 0.949, is anchored at 0 (dead) and 1 (full health). EQ VAS self-rating records the respondent's own assessment of his/her overall health status at time of completion, on a scale of 0 (worst health you can imagine) to 100 (best health you can imagine). Sum score ranges from 0 to 100 where, sum score = (sum of the scores from the 5 dimensions minus 5) *5. Higher score indicates worst health state.

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)

Participants self-administered (under direct supervision by HCP) esketamine matched placebo intranasally twice weekly for 4 weeks (on Day 1,4,8,11,15,18,22 and 25). Simultaneously, participants initiated per fixed titration scheme a new open-label oral AD with one of following: [Duloxetine (60 milligram (mg)/day- Weeks 1-4 with minimum dose for tolerability [MDT] of 60 mg/day); Escitalopram (10 mg/day- Week 1 and 20 mg/day- Weeks 2-4 with MDT of 10 mg/day); Sertraline (50 mg/day- Week 1, 100 mg/day- Week 2, 150 mg/day- Week 3 and 200 mg/day- Week 4 with MDT of 50 mg/day) or Venlafaxine XR (75 mg/day- Week 1, 150 mg/day- Week 2, and 225 mg/day- Weeks 3 and 4 with MDT of 150 mg/day) during DB Induction Phase. Participants who were not eligible or who chose to not participate in maintenance of effect study (ESKETINTRD3003 [NCT02493868]) and had received at least 1 dose of intranasal Placebo+ Oral AD in DB induction phase were followed in posttreatment follow-up phase for up to 24 weeks.](streamdown:incomplete-link)